// Copyright 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/viz/service/display/gl_renderer.h"

#include <stddef.h>
#include <stdint.h>

#include <algorithm>
#include <limits>
#include <memory>
#include <numeric>
#include <set>
#include <string>
#include <utility>
#include <vector>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/feature_list.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/trace_event/trace_event.h"
#include "build/build_config.h"
#include "cc/base/math_util.h"
#include "cc/debug/debug_colors.h"
#include "cc/paint/render_surface_filters.h"
#include "cc/raster/scoped_gpu_raster.h"
#include "components/viz/common/display/renderer_settings.h"
#include "components/viz/common/frame_sinks/copy_output_request.h"
#include "components/viz/common/gpu/context_provider.h"
#include "components/viz/common/quads/compositor_frame.h"
#include "components/viz/common/quads/compositor_frame_metadata.h"
#include "components/viz/common/quads/picture_draw_quad.h"
#include "components/viz/common/quads/render_pass.h"
#include "components/viz/common/quads/stream_video_draw_quad.h"
#include "components/viz/common/quads/texture_draw_quad.h"
#include "components/viz/common/resources/platform_color.h"
#include "components/viz/common/resources/resource_format_utils.h"
#include "components/viz/common/resources/resource_id.h"
#include "components/viz/common/skia_helper.h"
#include "components/viz/service/display/draw_polygon.h"
#include "components/viz/service/display/dynamic_geometry_binding.h"
#include "components/viz/service/display/layer_quad.h"
#include "components/viz/service/display/output_surface.h"
#include "components/viz/service/display/output_surface_frame.h"
#include "components/viz/service/display/resource_fence.h"
#include "components/viz/service/display/scoped_render_pass_texture.h"
#include "components/viz/service/display/static_geometry_binding.h"
#include "components/viz/service/display/texture_deleter.h"
#include "gpu/GLES2/gl2extchromium.h"
#include "gpu/command_buffer/client/context_support.h"
#include "gpu/command_buffer/client/gles2_interface.h"
#include "gpu/command_buffer/common/gpu_memory_allocation.h"
#include "media/base/media_switches.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkColor.h"
#include "third_party/skia/include/core/SkColorFilter.h"
#include "third_party/skia/include/core/SkImage.h"
#include "third_party/skia/include/core/SkSurface.h"
#include "third_party/skia/include/gpu/GrBackendSurface.h"
#include "third_party/skia/include/gpu/GrContext.h"
#include "third_party/skia/include/gpu/gl/GrGLInterface.h"
#include "third_party/skia/include/gpu/gl/GrGLTypes.h"
#include "ui/gfx/color_space.h"
#include "ui/gfx/color_transform.h"
#include "ui/gfx/geometry/quad_f.h"
#include "ui/gfx/geometry/rect_conversions.h"
#include "ui/gfx/geometry/size_conversions.h"
#include "ui/gfx/skia_util.h"

using gpu::gles2::GLES2Interface;

namespace viz {
namespace {

Float4 UVTransform(const TextureDrawQuad* quad) {
  gfx::PointF uv0 = quad->uv_top_left;
  gfx::PointF uv1 = quad->uv_bottom_right;
  Float4 xform = {{uv0.x(), uv0.y(), uv1.x() - uv0.x(), uv1.y() - uv0.y()}};
  if (quad->y_flipped) {
    xform.data[1] = 1.0f - xform.data[1];
    xform.data[3] = -xform.data[3];
  }
  return xform;
}

// To prevent sampling outside the visible rect.
Float4 UVClampRect(gfx::RectF uv_visible_rect,
                   const gfx::Size& texture_size,
                   SamplerType sampler) {
  gfx::SizeF half_texel(0.5f, 0.5f);
  if (sampler != SAMPLER_TYPE_2D_RECT) {
    half_texel.Scale(1.f / texture_size.width(), 1.f / texture_size.height());
  } else {
    uv_visible_rect.Scale(texture_size.width(), texture_size.height());
  }
  uv_visible_rect.Inset(half_texel.width(), half_texel.height());
  return {{uv_visible_rect.x(), uv_visible_rect.y(), uv_visible_rect.right(),
           uv_visible_rect.bottom()}};
}

Float4 PremultipliedColor(SkColor color, float opacity) {
  const float factor = 1.0f / 255.0f;
  const float alpha = opacity * SkColorGetA(color) * factor;

  Float4 result = {{SkColorGetR(color) * factor * alpha,
                    SkColorGetG(color) * factor * alpha,
                    SkColorGetB(color) * factor * alpha, alpha}};
  return result;
}

SamplerType SamplerTypeFromTextureTarget(GLenum target) {
  switch (target) {
    case GL_TEXTURE_2D:
      return SAMPLER_TYPE_2D;
    case GL_TEXTURE_RECTANGLE_ARB:
      return SAMPLER_TYPE_2D_RECT;
    case GL_TEXTURE_EXTERNAL_OES:
      return SAMPLER_TYPE_EXTERNAL_OES;
    default:
      NOTREACHED();
      return SAMPLER_TYPE_2D;
  }
}

BlendMode BlendModeFromSkXfermode(SkBlendMode mode) {
  switch (mode) {
    case SkBlendMode::kSrcOver:
      return BLEND_MODE_NORMAL;
    case SkBlendMode::kDstIn:
      return BLEND_MODE_DESTINATION_IN;
    case SkBlendMode::kScreen:
      return BLEND_MODE_SCREEN;
    case SkBlendMode::kOverlay:
      return BLEND_MODE_OVERLAY;
    case SkBlendMode::kDarken:
      return BLEND_MODE_DARKEN;
    case SkBlendMode::kLighten:
      return BLEND_MODE_LIGHTEN;
    case SkBlendMode::kColorDodge:
      return BLEND_MODE_COLOR_DODGE;
    case SkBlendMode::kColorBurn:
      return BLEND_MODE_COLOR_BURN;
    case SkBlendMode::kHardLight:
      return BLEND_MODE_HARD_LIGHT;
    case SkBlendMode::kSoftLight:
      return BLEND_MODE_SOFT_LIGHT;
    case SkBlendMode::kDifference:
      return BLEND_MODE_DIFFERENCE;
    case SkBlendMode::kExclusion:
      return BLEND_MODE_EXCLUSION;
    case SkBlendMode::kMultiply:
      return BLEND_MODE_MULTIPLY;
    case SkBlendMode::kHue:
      return BLEND_MODE_HUE;
    case SkBlendMode::kSaturation:
      return BLEND_MODE_SATURATION;
    case SkBlendMode::kColor:
      return BLEND_MODE_COLOR;
    case SkBlendMode::kLuminosity:
      return BLEND_MODE_LUMINOSITY;
    default:
      NOTREACHED();
      return BLEND_MODE_NONE;
  }
}

// Smallest unit that impact anti-aliasing output. We use this to
// determine when anti-aliasing is unnecessary.
const float kAntiAliasingEpsilon = 1.0f / 1024.0f;
}  // anonymous namespace

static GLint GetActiveTextureUnit(GLES2Interface* gl) {
  GLint active_unit = 0;
  gl->GetIntegerv(GL_ACTIVE_TEXTURE, &active_unit);
  return active_unit;
}

// Parameters needed to draw a RenderPassDrawQuad.
struct GLRenderer::DrawRenderPassDrawQuadParams {
  DrawRenderPassDrawQuadParams() {}
  ~DrawRenderPassDrawQuadParams() {
    // Don't leak the texture.
    DCHECK(!background_texture);
  }

  // Required inputs below.
  const RenderPassDrawQuad* quad = nullptr;

  // Either |contents_texture| or |bypass_quad_texture| is populated. The
  // |contents_texture| will be valid if non-null, and when null the
  // bypass_quad_texture will be valid instead.
  ScopedRenderPassTexture* contents_texture = nullptr;
  struct {
    ResourceId resource_id = 0;
    gfx::Size size;
  } bypass_quad_texture;

  const gfx::QuadF* clip_region = nullptr;
  bool flip_texture = false;
  gfx::Transform window_matrix;
  gfx::Transform projection_matrix;
  gfx::Transform quad_to_target_transform;
  const cc::FilterOperations* filters = nullptr;
  const cc::FilterOperations* background_filters = nullptr;

  // Whether the texture to be sampled from needs to be flipped.
  bool source_needs_flip = false;

  float edge[24];
  SkScalar color_matrix[20];

  // Blending refers to modifications to the backdrop.
  bool use_shaders_for_blending = false;

  bool use_aa = false;

  // Some filters affect pixels outside the original contents bounds, in which
  // case ApplyImageFilter will modify this rect.
  gfx::RectF dst_rect;

  // A Skia image that should be sampled from instead of the original
  // contents.
  sk_sp<SkImage> filter_image;

  // The original contents, bound for sampling.
  std::unique_ptr<DisplayResourceProvider::ScopedSamplerGL>
      bypass_quad_resource_lock;

  // A mask to be applied when drawing the RPDQ.
  std::unique_ptr<DisplayResourceProvider::ScopedSamplerGL> mask_resource_lock;

  // Whether a color matrix needs to be applied by the shaders when drawing
  // the RPDQ.
  bool use_color_matrix = false;

  gfx::QuadF surface_quad;

  gfx::Transform contents_device_transform;

  gfx::RectF tex_coord_rect;

  // The color space of the texture bound for sampling (from filter_image or
  // bypass_quad_resource_lock, depending on the path taken).
  gfx::ColorSpace contents_and_bypass_color_space;

  // Background filters block.
  // Original background texture.
  uint32_t background_texture = 0;
  // Backdrop bounding box.
  gfx::Rect background_rect;
  // Filtered background texture.
  sk_sp<SkImage> background_image;
  GLuint background_image_id = 0;
  // Whether the original background texture is needed for the mask.
  bool mask_for_background = false;
};

class GLRenderer::ScopedUseGrContext {
 public:
  static std::unique_ptr<ScopedUseGrContext> Create(GLRenderer* renderer) {
    // GrContext for filters is created lazily, and may fail if the context
    // is lost.
    // TODO(vmiura,bsalomon): crbug.com/487850 Ensure that
    // ContextProvider::GrContext() does not return NULL.
    if (renderer->output_surface_->context_provider()->GrContext())
      return base::WrapUnique(new ScopedUseGrContext(renderer));
    return nullptr;
  }

  ~ScopedUseGrContext() {
    // Pass context control back to GLrenderer.
    scoped_gpu_raster_ = nullptr;
    renderer_->RestoreGLState();
  }

  GrContext* context() const {
    return renderer_->output_surface_->context_provider()->GrContext();
  }

 private:
  explicit ScopedUseGrContext(GLRenderer* renderer)
      : scoped_gpu_raster_(new cc::ScopedGpuRaster(
            renderer->output_surface_->context_provider())),
        renderer_(renderer) {
    // scoped_gpu_raster_ passes context control to Skia.
  }

  std::unique_ptr<cc::ScopedGpuRaster> scoped_gpu_raster_;
  GLRenderer* renderer_;

  DISALLOW_COPY_AND_ASSIGN(ScopedUseGrContext);
};

GLRenderer::GLRenderer(
    const RendererSettings* settings,
    OutputSurface* output_surface,
    DisplayResourceProvider* resource_provider,
    scoped_refptr<base::SingleThreadTaskRunner> current_task_runner)
    : DirectRenderer(settings, output_surface, resource_provider),
      shared_geometry_quad_(QuadVertexRect()),
      gl_(output_surface->context_provider()->ContextGL()),
      context_support_(output_surface->context_provider()->ContextSupport()),
      texture_deleter_(current_task_runner),
      copier_(output_surface->context_provider(),
              &texture_deleter_,
              base::BindRepeating(&GLRenderer::MoveFromDrawToWindowSpace,
                                  base::Unretained(this))),
      sync_queries_(gl_),
      bound_geometry_(NO_BINDING),
      color_lut_cache_(gl_,
                       output_surface_->context_provider()
                           ->ContextCapabilities()
                           .texture_half_float_linear),
      current_task_runner_(std::move(current_task_runner)),
      weak_ptr_factory_(this) {
  DCHECK(gl_);
  DCHECK(context_support_);

  const auto& context_caps =
      output_surface_->context_provider()->ContextCapabilities();
  DCHECK(!context_caps.iosurface || context_caps.texture_rectangle);

  use_discard_framebuffer_ = context_caps.discard_framebuffer;
  use_sync_query_ = context_caps.sync_query;
  use_blend_equation_advanced_ = context_caps.blend_equation_advanced;
  use_blend_equation_advanced_coherent_ =
      context_caps.blend_equation_advanced_coherent;
  use_occlusion_query_ = context_caps.occlusion_query;
  use_swap_with_bounds_ = context_caps.swap_buffers_with_bounds;

  InitializeSharedObjects();
}

GLRenderer::~GLRenderer() {
  CleanupSharedObjects();

  if (context_visibility_) {
    auto* context_provider = output_surface_->context_provider();
    auto* cache_controller = context_provider->CacheController();
    cache_controller->ClientBecameNotVisible(std::move(context_visibility_));
  }
}

bool GLRenderer::CanPartialSwap() {
  if (use_swap_with_bounds_)
    return false;
  auto* context_provider = output_surface_->context_provider();
  return context_provider->ContextCapabilities().post_sub_buffer;
}

void GLRenderer::DidChangeVisibility() {
  if (visible_) {
    output_surface_->EnsureBackbuffer();
  } else {
    TRACE_EVENT0("viz", "GLRenderer::DidChangeVisibility dropping resources");
    ReleaseRenderPassTextures();
    output_surface_->DiscardBackbuffer();
    gl_->ReleaseShaderCompiler();
  }

  PrepareGeometry(NO_BINDING);

  auto* context_provider = output_surface_->context_provider();
  auto* cache_controller = context_provider->CacheController();
  if (visible_) {
    DCHECK(!context_visibility_);
    context_visibility_ = cache_controller->ClientBecameVisible();
  } else {
    DCHECK(context_visibility_);
    cache_controller->ClientBecameNotVisible(std::move(context_visibility_));
  }
}

void GLRenderer::ReleaseRenderPassTextures() {
  render_pass_textures_.clear();
}

void GLRenderer::DiscardPixels() {
  if (!use_discard_framebuffer_)
    return;
  bool using_default_framebuffer =
      !current_framebuffer_texture_ &&
      output_surface_->capabilities().uses_default_gl_framebuffer;
  GLenum attachments[] = {static_cast<GLenum>(
      using_default_framebuffer ? GL_COLOR_EXT : GL_COLOR_ATTACHMENT0_EXT)};
  gl_->DiscardFramebufferEXT(GL_FRAMEBUFFER, arraysize(attachments),
                             attachments);
}

void GLRenderer::PrepareSurfaceForPass(
    SurfaceInitializationMode initialization_mode,
    const gfx::Rect& render_pass_scissor) {
  SetViewport();

  switch (initialization_mode) {
    case SURFACE_INITIALIZATION_MODE_PRESERVE:
      EnsureScissorTestDisabled();
      return;
    case SURFACE_INITIALIZATION_MODE_FULL_SURFACE_CLEAR:
      EnsureScissorTestDisabled();
      DiscardPixels();
      ClearFramebuffer();
      break;
    case SURFACE_INITIALIZATION_MODE_SCISSORED_CLEAR:
      SetScissorTestRect(render_pass_scissor);
      ClearFramebuffer();
      break;
  }
}

void GLRenderer::ClearFramebuffer() {
  // On DEBUG builds, opaque render passes are cleared to blue to easily see
  // regions that were not drawn on the screen.
  if (current_frame()->current_render_pass->has_transparent_background)
    gl_->ClearColor(0, 0, 0, 0);
  else
    gl_->ClearColor(0, 0, 1, 1);

  gl_->ClearStencil(0);

  bool always_clear = overdraw_feedback_;
#ifndef NDEBUG
  always_clear = true;
#endif
  if (always_clear ||
      current_frame()->current_render_pass->has_transparent_background) {
    GLbitfield clear_bits = GL_COLOR_BUFFER_BIT;
    if (always_clear)
      clear_bits |= GL_STENCIL_BUFFER_BIT;
    gl_->Clear(clear_bits);
  }
}

void GLRenderer::BeginDrawingFrame() {
  TRACE_EVENT0("viz", "GLRenderer::BeginDrawingFrame");

  scoped_refptr<ResourceFence> read_lock_fence;
  if (use_sync_query_) {
    read_lock_fence = sync_queries_.StartNewFrame();
  } else {
    read_lock_fence =
        base::MakeRefCounted<DisplayResourceProvider::SynchronousFence>(gl_);
  }
  resource_provider_->SetReadLockFence(read_lock_fence.get());

  // Insert WaitSyncTokenCHROMIUM on quad resources prior to drawing the frame,
  // so that drawing can proceed without GL context switching interruptions.
  for (const auto& pass : *current_frame()->render_passes_in_draw_order) {
    for (auto* quad : pass->quad_list) {
      for (ResourceId resource_id : quad->resources)
        resource_provider_->WaitSyncToken(resource_id);
    }
  }

  // TODO(enne): Do we need to reinitialize all of this state per frame?
  ReinitializeGLState();

  num_triangles_drawn_ = 0;
}

void GLRenderer::DoDrawQuad(const DrawQuad* quad,
                            const gfx::QuadF* clip_region) {
  DCHECK(quad->rect.Contains(quad->visible_rect));
  if (quad->material != DrawQuad::TEXTURE_CONTENT) {
    FlushTextureQuadCache(SHARED_BINDING);
  }

  switch (quad->material) {
    case DrawQuad::INVALID:
      NOTREACHED();
      break;
    case DrawQuad::DEBUG_BORDER:
      DrawDebugBorderQuad(DebugBorderDrawQuad::MaterialCast(quad));
      break;
    case DrawQuad::PICTURE_CONTENT:
      // PictureDrawQuad should only be used for resourceless software draws.
      NOTREACHED();
      break;
    case DrawQuad::RENDER_PASS:
      DrawRenderPassQuad(RenderPassDrawQuad::MaterialCast(quad), clip_region);
      break;
    case DrawQuad::SOLID_COLOR:
      DrawSolidColorQuad(SolidColorDrawQuad::MaterialCast(quad), clip_region);
      break;
    case DrawQuad::STREAM_VIDEO_CONTENT:
      DrawStreamVideoQuad(StreamVideoDrawQuad::MaterialCast(quad), clip_region);
      break;
    case DrawQuad::SURFACE_CONTENT:
      // Surface content should be fully resolved to other quad types before
      // reaching a direct renderer.
      NOTREACHED();
      break;
    case DrawQuad::TEXTURE_CONTENT:
      EnqueueTextureQuad(TextureDrawQuad::MaterialCast(quad), clip_region);
      break;
    case DrawQuad::TILED_CONTENT:
      DrawTileQuad(TileDrawQuad::MaterialCast(quad), clip_region);
      break;
    case DrawQuad::YUV_VIDEO_CONTENT:
      DrawYUVVideoQuad(YUVVideoDrawQuad::MaterialCast(quad), clip_region);
      break;
  }
}

// This function does not handle 3D sorting right now, since the debug border
// quads are just drawn as their original quads and not in split pieces. This
// results in some debug border quads drawing over foreground quads.
void GLRenderer::DrawDebugBorderQuad(const DebugBorderDrawQuad* quad) {
  SetBlendEnabled(quad->ShouldDrawWithBlending());

  SetUseProgram(ProgramKey::DebugBorder(), gfx::ColorSpace::CreateSRGB(),
                current_frame()->current_render_pass->color_space);

  // Use the full quad_rect for debug quads to not move the edges based on
  // partial swaps.
  gfx::Rect layer_rect = quad->rect;
  gfx::Transform render_matrix;
  QuadRectTransform(&render_matrix,
                    quad->shared_quad_state->quad_to_target_transform,
                    gfx::RectF(layer_rect));
  SetShaderMatrix(current_frame()->projection_matrix * render_matrix);
  SetShaderColor(quad->color, 1.f);

  gl_->LineWidth(quad->width);

  // The indices for the line are stored in the same array as the triangle
  // indices.
  gl_->DrawElements(GL_LINE_LOOP, 4, GL_UNSIGNED_SHORT, nullptr);
}

// Wrap a given texture in a Ganesh backend texture.
static sk_sp<SkImage> WrapTexture(uint32_t texture_id,
                                  uint32_t target,
                                  const gfx::Size& size,
                                  GrContext* context,
                                  bool flip_texture) {
  GrGLTextureInfo texture_info;
  texture_info.fTarget = target;
  texture_info.fID = texture_id;
  if (kN32_SkColorType == kRGBA_8888_SkColorType) {
    texture_info.fFormat = GL_RGBA8_OES;
  } else {
    DCHECK(kN32_SkColorType == kBGRA_8888_SkColorType);
    texture_info.fFormat = GL_BGRA8_EXT;
  }
  GrBackendTexture backend_texture(size.width(), size.height(),
                                   GrMipMapped::kNo, texture_info);
  GrSurfaceOrigin origin =
      flip_texture ? kBottomLeft_GrSurfaceOrigin : kTopLeft_GrSurfaceOrigin;

  return SkImage::MakeFromTexture(context, backend_texture, origin,
                                  kN32_SkColorType, kPremul_SkAlphaType,
                                  nullptr);
}

static gfx::RectF CenteredRect(const gfx::Rect& tile_rect) {
  return gfx::RectF(
      gfx::PointF(-0.5f * tile_rect.width(), -0.5f * tile_rect.height()),
      gfx::SizeF(tile_rect.size()));
}

bool GLRenderer::CanApplyBlendModeUsingBlendFunc(SkBlendMode blend_mode) {
  return use_blend_equation_advanced_ || blend_mode == SkBlendMode::kSrcOver ||
         blend_mode == SkBlendMode::kDstIn ||
         blend_mode == SkBlendMode::kScreen;
}

void GLRenderer::ApplyBlendModeUsingBlendFunc(SkBlendMode blend_mode) {
  // Any modes set here must be reset in RestoreBlendFuncToDefault
  if (blend_mode == SkBlendMode::kSrcOver) {
    // Left no-op intentionally.
  } else if (blend_mode == SkBlendMode::kDstIn) {
    gl_->BlendFunc(GL_ZERO, GL_SRC_ALPHA);
  } else if (blend_mode == SkBlendMode::kDstOut) {
    gl_->BlendFunc(GL_ZERO, GL_ONE_MINUS_SRC_ALPHA);
  } else if (blend_mode == SkBlendMode::kScreen) {
    gl_->BlendFunc(GL_ONE_MINUS_DST_COLOR, GL_ONE);
  } else {
    DCHECK(use_blend_equation_advanced_);
    GLenum equation = GL_FUNC_ADD;
    switch (blend_mode) {
      case SkBlendMode::kScreen:
        equation = GL_SCREEN_KHR;
        break;
      case SkBlendMode::kOverlay:
        equation = GL_OVERLAY_KHR;
        break;
      case SkBlendMode::kDarken:
        equation = GL_DARKEN_KHR;
        break;
      case SkBlendMode::kLighten:
        equation = GL_LIGHTEN_KHR;
        break;
      case SkBlendMode::kColorDodge:
        equation = GL_COLORDODGE_KHR;
        break;
      case SkBlendMode::kColorBurn:
        equation = GL_COLORBURN_KHR;
        break;
      case SkBlendMode::kHardLight:
        equation = GL_HARDLIGHT_KHR;
        break;
      case SkBlendMode::kSoftLight:
        equation = GL_SOFTLIGHT_KHR;
        break;
      case SkBlendMode::kDifference:
        equation = GL_DIFFERENCE_KHR;
        break;
      case SkBlendMode::kExclusion:
        equation = GL_EXCLUSION_KHR;
        break;
      case SkBlendMode::kMultiply:
        equation = GL_MULTIPLY_KHR;
        break;
      case SkBlendMode::kHue:
        equation = GL_HSL_HUE_KHR;
        break;
      case SkBlendMode::kSaturation:
        equation = GL_HSL_SATURATION_KHR;
        break;
      case SkBlendMode::kColor:
        equation = GL_HSL_COLOR_KHR;
        break;
      case SkBlendMode::kLuminosity:
        equation = GL_HSL_LUMINOSITY_KHR;
        break;
      default:
        NOTREACHED() << "Unexpected blend mode: SkBlendMode::k"
                     << SkBlendMode_Name(blend_mode);
        return;
    }
    gl_->BlendEquation(equation);
  }
}

void GLRenderer::RestoreBlendFuncToDefault(SkBlendMode blend_mode) {
  switch (blend_mode) {
    case SkBlendMode::kSrcOver:
      break;
    case SkBlendMode::kDstIn:
    case SkBlendMode::kDstOut:
    case SkBlendMode::kScreen:
      gl_->BlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
      break;
    default:
      DCHECK(use_blend_equation_advanced_);
      gl_->BlendEquation(GL_FUNC_ADD);
  }
}

bool GLRenderer::ShouldApplyBackgroundFilters(
    const RenderPassDrawQuad* quad,
    const cc::FilterOperations* background_filters) {
  if (!background_filters)
    return false;
  DCHECK(!background_filters->IsEmpty());

  // TODO(hendrikw): Look into allowing background filters to see pixels from
  // other render targets.  See crbug.com/314867.

  return true;
}

// This takes a gfx::Rect and a clip region quad in the same space,
// and returns a quad with the same proportions in the space -0.5->0.5.
bool GetScaledRegion(const gfx::Rect& rect,
                     const gfx::QuadF* clip,
                     gfx::QuadF* scaled_region) {
  if (!clip)
    return false;

  gfx::PointF p1(((clip->p1().x() - rect.x()) / rect.width()) - 0.5f,
                 ((clip->p1().y() - rect.y()) / rect.height()) - 0.5f);
  gfx::PointF p2(((clip->p2().x() - rect.x()) / rect.width()) - 0.5f,
                 ((clip->p2().y() - rect.y()) / rect.height()) - 0.5f);
  gfx::PointF p3(((clip->p3().x() - rect.x()) / rect.width()) - 0.5f,
                 ((clip->p3().y() - rect.y()) / rect.height()) - 0.5f);
  gfx::PointF p4(((clip->p4().x() - rect.x()) / rect.width()) - 0.5f,
                 ((clip->p4().y() - rect.y()) / rect.height()) - 0.5f);
  *scaled_region = gfx::QuadF(p1, p2, p3, p4);
  return true;
}

// This takes a gfx::Rect and a clip region quad in the same space,
// and returns the proportional uv's in the space 0->1.
bool GetScaledUVs(const gfx::Rect& rect, const gfx::QuadF* clip, float uvs[8]) {
  if (!clip)
    return false;

  uvs[0] = ((clip->p1().x() - rect.x()) / rect.width());
  uvs[1] = ((clip->p1().y() - rect.y()) / rect.height());
  uvs[2] = ((clip->p2().x() - rect.x()) / rect.width());
  uvs[3] = ((clip->p2().y() - rect.y()) / rect.height());
  uvs[4] = ((clip->p3().x() - rect.x()) / rect.width());
  uvs[5] = ((clip->p3().y() - rect.y()) / rect.height());
  uvs[6] = ((clip->p4().x() - rect.x()) / rect.width());
  uvs[7] = ((clip->p4().y() - rect.y()) / rect.height());
  return true;
}

gfx::Rect GLRenderer::GetBackdropBoundingBoxForRenderPassQuad(
    const RenderPassDrawQuad* quad,
    const gfx::Transform& contents_device_transform,
    const cc::FilterOperations* filters,
    const cc::FilterOperations* background_filters,
    const gfx::QuadF* clip_region,
    bool use_aa,
    gfx::Rect* unclipped_rect) {
  gfx::QuadF scaled_region;
  if (!GetScaledRegion(quad->rect, clip_region, &scaled_region)) {
    scaled_region = SharedGeometryQuad().BoundingBox();
  }

  gfx::Rect backdrop_rect = gfx::ToEnclosingRect(cc::MathUtil::MapClippedRect(
      contents_device_transform, scaled_region.BoundingBox()));

  if (ShouldApplyBackgroundFilters(quad, background_filters)) {
    SkMatrix matrix;
    matrix.setScale(quad->filters_scale.x(), quad->filters_scale.y());
    if (FlippedFramebuffer()) {
      // TODO(jbroman): This probably isn't the right way to account for this.
      // Probably some combination of current_frame()->projection_matrix,
      // current_frame()->window_matrix and contents_device_transform?
      matrix.postScale(1, -1);
    }
    backdrop_rect = background_filters->MapRectReverse(backdrop_rect, matrix);
  }

  if (!backdrop_rect.IsEmpty() && use_aa) {
    const int kOutsetForAntialiasing = 1;
    backdrop_rect.Inset(-kOutsetForAntialiasing, -kOutsetForAntialiasing);
  }

  if (filters) {
    DCHECK(!filters->IsEmpty());
    // If we have filters, grab an extra one-pixel border around the
    // background, so texture edge clamping gives us a transparent border
    // in case the filter expands the result.
    backdrop_rect.Inset(-1, -1, -1, -1);
  }

  *unclipped_rect = backdrop_rect;
  backdrop_rect.Intersect(MoveFromDrawToWindowSpace(
      current_frame()->current_render_pass->output_rect));
  return backdrop_rect;
}

GLenum GLRenderer::GetFramebufferCopyTextureFormat() {
  // If copying a non-root renderpass then use the format of the bound
  // texture. Otherwise, we use the format of the default framebuffer. But
  // whatever the format is, convert it to a valid format for CopyTexSubImage2D.
  GLenum format;
  if (!current_framebuffer_texture_) {
    format = output_surface_->GetFramebufferCopyTextureFormat();
  } else {
    ResourceFormat resource_format = BackbufferFormat();
    DCHECK(GLSupportsFormat(resource_format));
    format = GLCopyTextureInternalFormat(resource_format);
  }
  // Verify the format is valid for GLES2's glCopyTexSubImage2D.
  DCHECK(format == GL_ALPHA || format == GL_LUMINANCE ||
         format == GL_LUMINANCE_ALPHA || format == GL_RGB ||
         format == GL_RGBA ||
         (output_surface_->context_provider()
              ->ContextCapabilities()
              .texture_format_bgra8888 &&
          format == GL_BGRA_EXT))
      << format;
  return format;
}

uint32_t GLRenderer::GetBackdropTexture(const gfx::Rect& window_rect) {
  DCHECK_GE(window_rect.x(), 0);
  DCHECK_GE(window_rect.y(), 0);
  DCHECK_LE(window_rect.right(), current_surface_size_.width());
  DCHECK_LE(window_rect.bottom(), current_surface_size_.height());

  uint32_t texture_id;
  gl_->GenTextures(1, &texture_id);
  gl_->BindTexture(GL_TEXTURE_2D, texture_id);

  gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

  gl_->BindTexture(GL_TEXTURE_2D, texture_id);
  gl_->CopyTexImage2D(GL_TEXTURE_2D, 0, GetFramebufferCopyTextureFormat(),
                      window_rect.x(), window_rect.y(), window_rect.width(),
                      window_rect.height(), 0);
  gl_->BindTexture(GL_TEXTURE_2D, 0);
  return texture_id;
}

sk_sp<SkImage> GLRenderer::ApplyBackgroundFilters(
    const RenderPassDrawQuad* quad,
    const cc::FilterOperations& background_filters,
    uint32_t background_texture,
    const gfx::Rect& rect,
    const gfx::Rect& unclipped_rect) {
  DCHECK(ShouldApplyBackgroundFilters(quad, &background_filters));
  auto use_gr_context = ScopedUseGrContext::Create(this);

  gfx::Vector2d clipping_offset =
      (rect.top_right() - unclipped_rect.top_right()) +
      (rect.bottom_left() - unclipped_rect.bottom_left());
  auto paint_filter = cc::RenderSurfaceFilters::BuildImageFilter(
      background_filters, gfx::SizeF(rect.size()),
      gfx::Vector2dF(clipping_offset));

  // TODO(senorblanco): background filters should be moved to the
  // makeWithFilter fast-path, and go back to calling ApplyImageFilter().
  // See http://crbug.com/613233.
  if (!paint_filter || !use_gr_context)
    return nullptr;

  auto filter = paint_filter->cached_sk_filter_;
  bool flip_texture = true;
  sk_sp<SkImage> src_image =
      WrapTexture(background_texture, GL_TEXTURE_2D, rect.size(),
                  use_gr_context->context(), flip_texture);
  if (!src_image) {
    TRACE_EVENT_INSTANT0(
        "cc", "ApplyBackgroundFilters wrap background texture failed",
        TRACE_EVENT_SCOPE_THREAD);
    return nullptr;
  }

  // Create surface to draw into.
  SkImageInfo dst_info =
      SkImageInfo::MakeN32Premul(rect.width(), rect.height());
  sk_sp<SkSurface> surface = SkSurface::MakeRenderTarget(
      use_gr_context->context(), SkBudgeted::kYes, dst_info);
  if (!surface) {
    TRACE_EVENT_INSTANT0("viz",
                         "ApplyBackgroundFilters surface allocation failed",
                         TRACE_EVENT_SCOPE_THREAD);
    return nullptr;
  }

  // Big filters can sometimes fallback to CPU. Therefore, we need
  // to disable subnormal floats for performance and security reasons.
  cc::ScopedSubnormalFloatDisabler disabler;
  SkMatrix local_matrix;
  local_matrix.setScale(quad->filters_scale.x(), quad->filters_scale.y());

  SkPaint paint;
  paint.setImageFilter(filter->makeWithLocalMatrix(local_matrix));
  surface->getCanvas()->translate(-rect.x(), -rect.y());
  surface->getCanvas()->drawImage(src_image, rect.x(), rect.y(), &paint);
  // Flush the drawing before source texture read lock goes out of scope.
  // Skia API does not guarantee that when the SkImage goes out of scope,
  // its externally referenced resources would force the rendering to be
  // flushed.
  surface->getCanvas()->flush();
  sk_sp<SkImage> image = surface->makeImageSnapshot();
  if (!image || !image->isTextureBacked()) {
    return nullptr;
  }

  return image;
}

const TileDrawQuad* GLRenderer::CanPassBeDrawnDirectly(const RenderPass* pass) {
#if defined(OS_MACOSX)
  // On Macs, this path can sometimes lead to all black output.
  // TODO(enne): investigate this and remove this hack.
  return nullptr;
#endif

  // Can only collapse a single tile quad.
  if (pass->quad_list.size() != 1)
    return nullptr;
  // If we need copy requests, then render pass has to exist.
  if (!pass->copy_requests.empty())
    return nullptr;

  const DrawQuad* quad = *pass->quad_list.BackToFrontBegin();
  // Hack: this could be supported by concatenating transforms, but
  // in practice if there is one quad, it is at the origin of the render pass
  // and has the same size as the pass.
  if (!quad->shared_quad_state->quad_to_target_transform.IsIdentity() ||
      quad->rect != pass->output_rect)
    return nullptr;
  // The quad is expected to be the entire layer so that AA edges are correct.
  if (quad->shared_quad_state->quad_layer_rect != quad->rect)
    return nullptr;
  if (quad->material != DrawQuad::TILED_CONTENT)
    return nullptr;

  // TODO(chrishtr): support could be added for opacity, but care needs
  // to be taken to make sure it is correct w.r.t. non-commutative filters etc.
  if (quad->shared_quad_state->opacity != 1.0f)
    return nullptr;

  const TileDrawQuad* tile_quad = TileDrawQuad::MaterialCast(quad);
  // Hack: this could be supported by passing in a subrectangle to draw
  // render pass, although in practice if there is only one quad there
  // will be no border texels on the input.
  if (tile_quad->tex_coord_rect != gfx::RectF(tile_quad->rect))
    return nullptr;
  // Tile quad features not supported in render pass shaders.
  if (tile_quad->swizzle_contents || tile_quad->nearest_neighbor)
    return nullptr;
  // BUG=skia:3868, Skia currently doesn't support texture rectangle inputs.
  // See also the DCHECKs about GL_TEXTURE_2D in DrawRenderPassQuad.
  GLenum target =
      resource_provider_->GetResourceTextureTarget(tile_quad->resource_id());
  if (target != GL_TEXTURE_2D)
    return nullptr;

  return tile_quad;
}

void GLRenderer::DrawRenderPassQuad(const RenderPassDrawQuad* quad,
                                    const gfx::QuadF* clip_region) {
  auto bypass = render_pass_bypass_quads_.find(quad->render_pass_id);
  DrawRenderPassDrawQuadParams params;
  params.quad = quad;
  params.clip_region = clip_region;
  params.window_matrix = current_frame()->window_matrix;
  params.projection_matrix = current_frame()->projection_matrix;
  params.tex_coord_rect = quad->tex_coord_rect;
  if (bypass != render_pass_bypass_quads_.end()) {
    TileDrawQuad* tile_quad = &bypass->second;
    // The projection matrix used by GLRenderer has a flip.  As tile texture
    // inputs are oriented opposite to framebuffer outputs, don't flip via
    // texture coords and let the projection matrix naturallyd o it.
    params.flip_texture = false;
    params.bypass_quad_texture.resource_id = tile_quad->resource_id();
    params.bypass_quad_texture.size = tile_quad->texture_size;
    DrawRenderPassQuadInternal(&params);
  } else {
    auto contents_texture_it = render_pass_textures_.find(quad->render_pass_id);
    DCHECK(contents_texture_it->second.id());
    // See above comments about texture flipping.  When the input is a
    // render pass, it needs to an extra flip to be oriented correctly.
    params.flip_texture = true;
    params.contents_texture = &contents_texture_it->second;
    DrawRenderPassQuadInternal(&params);
  }

  if (params.background_texture) {
    gl_->DeleteTextures(1, &params.background_texture);
    params.background_texture = 0;
  }
}

void GLRenderer::DrawRenderPassQuadInternal(
    DrawRenderPassDrawQuadParams* params) {
  params->quad_to_target_transform =
      params->quad->shared_quad_state->quad_to_target_transform;
  if (!InitializeRPDQParameters(params))
    return;

  UpdateRPDQShadersForBlending(params);
  bool can_draw = UpdateRPDQWithSkiaFilters(params);
  // The above calls use ScopedUseGrContext which can change the bound
  // framebuffer, so we need to restore it for the current RenderPass.
  UseRenderPass(current_frame()->current_render_pass);
  // As part of restoring the framebuffer, we call SetViewport directly, rather
  // than through PrepareSurfaceForPass. PrepareSurfaceForPass also clears the
  // surface, which is not desired when restoring.
  SetViewport();

  if (!can_draw)
    return;

  UpdateRPDQTexturesForSampling(params);
  UpdateRPDQBlendMode(params);
  ChooseRPDQProgram(params, current_frame()->current_render_pass->color_space);
  UpdateRPDQUniforms(params);
  DrawRPDQ(*params);
}

bool GLRenderer::InitializeRPDQParameters(
    DrawRenderPassDrawQuadParams* params) {
  const RenderPassDrawQuad* quad = params->quad;
  SkMatrix local_matrix;
  local_matrix.setTranslate(quad->filters_origin.x(), quad->filters_origin.y());
  local_matrix.postScale(quad->filters_scale.x(), quad->filters_scale.y());
  params->filters = FiltersForPass(quad->render_pass_id);
  params->background_filters = BackgroundFiltersForPass(quad->render_pass_id);
  gfx::Rect dst_rect = params->filters
                           ? params->filters->MapRect(quad->rect, local_matrix)
                           : quad->rect;
  params->dst_rect.SetRect(static_cast<float>(dst_rect.x()),
                           static_cast<float>(dst_rect.y()),
                           static_cast<float>(dst_rect.width()),
                           static_cast<float>(dst_rect.height()));
  gfx::Transform quad_rect_matrix;
  gfx::Rect quad_layer_rect(quad->shared_quad_state->quad_layer_rect);
  if (params->filters)
    quad_layer_rect = params->filters->MapRect(quad_layer_rect, local_matrix);
  QuadRectTransform(&quad_rect_matrix, params->quad_to_target_transform,
                    gfx::RectF(quad_layer_rect));
  params->contents_device_transform =
      params->window_matrix * params->projection_matrix * quad_rect_matrix;
  params->contents_device_transform.FlattenTo2d();

  // Can only draw surface if device matrix is invertible.
  if (!params->contents_device_transform.IsInvertible())
    return false;

  // TODO(sunxd): unify the anti-aliasing logic of RPDQ and TileDrawQuad.
  params->surface_quad = SharedGeometryQuad();
  gfx::QuadF device_layer_quad;
  if (settings_->allow_antialiasing && !quad->force_anti_aliasing_off &&
      quad->IsEdge()) {
    bool clipped = false;
    device_layer_quad = cc::MathUtil::MapQuad(params->contents_device_transform,
                                              params->surface_quad, &clipped);
    params->use_aa = ShouldAntialiasQuad(device_layer_quad, clipped,
                                         settings_->force_antialiasing);
  }

  const gfx::QuadF* aa_quad = params->use_aa ? &device_layer_quad : nullptr;
  SetupRenderPassQuadForClippingAndAntialiasing(
      params->contents_device_transform, quad, aa_quad, params->clip_region,
      &params->surface_quad, params->edge);

  return true;
}

// Get a GL texture id from an SkImage. An optional origin pointer can be
// passed in which will be filled out with the origin for the texture
// backing the SkImage.
static GLuint GetGLTextureIDFromSkImage(const SkImage* image,
                                        GrSurfaceOrigin* origin = nullptr) {
  GrBackendTexture backend_texture = image->getBackendTexture(true, origin);
  if (!backend_texture.isValid()) {
    return 0;
  }
  GrGLTextureInfo info;
  bool result = backend_texture.getGLTextureInfo(&info);
  DCHECK(result);
  return info.fID;
}

void GLRenderer::UpdateRPDQShadersForBlending(
    DrawRenderPassDrawQuadParams* params) {
  const RenderPassDrawQuad* quad = params->quad;
  SkBlendMode blend_mode = quad->shared_quad_state->blend_mode;
  params->use_shaders_for_blending =
      !CanApplyBlendModeUsingBlendFunc(blend_mode) ||
      ShouldApplyBackgroundFilters(quad, params->background_filters) ||
      settings_->force_blending_with_shaders;

  if (params->use_shaders_for_blending) {
    // Compute a bounding box around the pixels that will be visible through
    // the quad.
    gfx::Rect unclipped_rect;
    params->background_rect = GetBackdropBoundingBoxForRenderPassQuad(
        quad, params->contents_device_transform, params->filters,
        params->background_filters, params->clip_region, params->use_aa,
        &unclipped_rect);

    if (!params->background_rect.IsEmpty()) {
      // The pixels from the filtered background should completely replace the
      // current pixel values.
      if (blend_enabled())
        SetBlendEnabled(false);

      // Read the pixels in the bounding box into a buffer R.
      // This function allocates a texture, which should contribute to the
      // amount of memory used by render surfaces:
      // LayerTreeHost::CalculateMemoryForRenderSurfaces.
      params->background_texture = GetBackdropTexture(params->background_rect);

      if (ShouldApplyBackgroundFilters(quad, params->background_filters) &&
          params->background_texture) {
        // Apply the background filters to R, so that it is applied in the
        // pixels' coordinate space.
        params->background_image = ApplyBackgroundFilters(
            quad, *params->background_filters, params->background_texture,
            params->background_rect, unclipped_rect);
        if (params->background_image) {
          params->background_image_id =
              GetGLTextureIDFromSkImage(params->background_image.get());
          DCHECK(params->background_image_id || IsContextLost());
        }
      }
    }

    if (!params->background_texture) {
      // Something went wrong with reading the backdrop.
      DCHECK(!params->background_image_id);
      params->use_shaders_for_blending = false;
    } else if (params->background_image_id) {
      // Reset original background texture if there is not any mask.
      if (!quad->mask_resource_id()) {
        gl_->DeleteTextures(1, &params->background_texture);
        params->background_texture = 0;
      }
    } else if (CanApplyBlendModeUsingBlendFunc(blend_mode) &&
               ShouldApplyBackgroundFilters(quad, params->background_filters)) {
      // Something went wrong with applying background filters to the backdrop.
      params->use_shaders_for_blending = false;
      gl_->DeleteTextures(1, &params->background_texture);
      params->background_texture = 0;
    }
  }

  // Need original background texture for mask?
  params->mask_for_background =
      params->background_texture &&  // Have original background texture
      params->background_image_id;   // Have mask texture
  // If we have background texture + background image, then we also have mask
  // resource.
  if (params->background_texture && params->background_image_id) {
    DCHECK(params->mask_for_background);
    DCHECK(quad->mask_resource_id());
  }

  DCHECK_EQ(params->background_texture || params->background_image_id,
            params->use_shaders_for_blending);
}

bool GLRenderer::UpdateRPDQWithSkiaFilters(
    DrawRenderPassDrawQuadParams* params) {
  const RenderPassDrawQuad* quad = params->quad;
  // Apply filters to the contents texture.
  if (params->filters) {
    DCHECK(!params->filters->IsEmpty());
    gfx::Size size = params->contents_texture
                         ? params->contents_texture->size()
                         : params->bypass_quad_texture.size;
    auto paint_filter = cc::RenderSurfaceFilters::BuildImageFilter(
        *params->filters, gfx::SizeF(size));
    auto filter = paint_filter ? paint_filter->cached_sk_filter_ : nullptr;
    if (filter) {
      SkColorFilter* colorfilter_rawptr = nullptr;
      filter->asColorFilter(&colorfilter_rawptr);
      sk_sp<SkColorFilter> cf(colorfilter_rawptr);

      if (cf && cf->asColorMatrix(params->color_matrix)) {
        // We have a color matrix at the root of the filter DAG; apply it
        // locally in the compositor and process the rest of the DAG (if any)
        // in Skia.
        params->use_color_matrix = true;
        filter = sk_ref_sp(filter->getInput(0));
      }
      if (filter) {
        gfx::Rect clip_rect = quad->shared_quad_state->clip_rect;
        if (clip_rect.IsEmpty()) {
          clip_rect = current_draw_rect_;
        }
        gfx::Transform transform = params->quad_to_target_transform;
        if (!transform.IsInvertible()) {
          return false;
        }
        gfx::QuadF clip_quad = gfx::QuadF(gfx::RectF(clip_rect));
        gfx::QuadF local_clip =
            cc::MathUtil::InverseMapQuadToLocalSpace(transform, clip_quad);
        params->dst_rect.Intersect(local_clip.BoundingBox());
        // If we've been fully clipped out (by crop rect or clipping), there's
        // nothing to draw.
        if (params->dst_rect.IsEmpty()) {
          return false;
        }
        SkIPoint offset;
        SkIRect subset;
        gfx::RectF src_rect(quad->rect);
        auto use_gr_context = ScopedUseGrContext::Create(this);
        if (!use_gr_context)
          return false;

        if (params->contents_texture) {
          params->contents_and_bypass_color_space =
              params->contents_texture->color_space();
          sk_sp<SkImage> src_image =
              WrapTexture(params->contents_texture->id(), GL_TEXTURE_2D,
                          params->contents_texture->size(),
                          use_gr_context->context(), params->flip_texture);
          params->filter_image = SkiaHelper::ApplyImageFilter(
              src_image, src_rect, params->dst_rect, quad->filters_scale,
              std::move(filter), &offset, &subset, quad->filters_origin);
        } else {
          DisplayResourceProvider::ScopedReadLockGL
              prefilter_bypass_quad_texture_lock(
                  resource_provider_, params->bypass_quad_texture.resource_id);
          params->contents_and_bypass_color_space =
              prefilter_bypass_quad_texture_lock.color_space();
          sk_sp<SkImage> src_image =
              WrapTexture(prefilter_bypass_quad_texture_lock.texture_id(),
                          prefilter_bypass_quad_texture_lock.target(),
                          prefilter_bypass_quad_texture_lock.size(),
                          use_gr_context->context(), params->flip_texture);
          params->filter_image = SkiaHelper::ApplyImageFilter(
              src_image, src_rect, params->dst_rect, quad->filters_scale,
              std::move(filter), &offset, &subset, quad->filters_origin);
        }

        if (!params->filter_image)
          return false;
        params->dst_rect =
            gfx::RectF(src_rect.x() + offset.fX, src_rect.y() + offset.fY,
                       subset.width(), subset.height());
        gfx::RectF tex_rect = gfx::RectF(gfx::PointF(subset.x(), subset.y()),
                                         params->dst_rect.size());
        params->tex_coord_rect = tex_rect;
      }
    }
  }
  return true;
}

void GLRenderer::UpdateRPDQTexturesForSampling(
    DrawRenderPassDrawQuadParams* params) {
  if (params->quad->mask_resource_id()) {
    params->mask_resource_lock.reset(
        new DisplayResourceProvider::ScopedSamplerGL(
            resource_provider_, params->quad->mask_resource_id(), GL_TEXTURE1,
            GL_LINEAR));
  }

  if (params->filter_image) {
    GrSurfaceOrigin origin;
    GLuint filter_image_id =
        GetGLTextureIDFromSkImage(params->filter_image.get(), &origin);
    DCHECK(filter_image_id || IsContextLost());
    DCHECK_EQ(GL_TEXTURE0, GetActiveTextureUnit(gl_));
    gl_->BindTexture(GL_TEXTURE_2D, filter_image_id);
    gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // |params->contents_and_bypass_color_space| was populated when
    // |params->filter_image| was populated.
    params->source_needs_flip = kBottomLeft_GrSurfaceOrigin == origin;
  } else if (params->contents_texture) {
    params->contents_texture->BindForSampling();
    params->contents_and_bypass_color_space =
        params->contents_texture->color_space();
    params->source_needs_flip = params->flip_texture;
  } else {
    params->bypass_quad_resource_lock =
        std::make_unique<DisplayResourceProvider::ScopedSamplerGL>(
            resource_provider_, params->bypass_quad_texture.resource_id,
            GL_LINEAR);
    DCHECK_EQ(static_cast<GLenum>(GL_TEXTURE_2D),
              params->bypass_quad_resource_lock->target());
    params->contents_and_bypass_color_space =
        params->bypass_quad_resource_lock->color_space();
    params->source_needs_flip = params->flip_texture;
  }
}

void GLRenderer::UpdateRPDQBlendMode(DrawRenderPassDrawQuadParams* params) {
  SkBlendMode blend_mode = params->quad->shared_quad_state->blend_mode;
  SetBlendEnabled(!params->use_shaders_for_blending &&
                  (params->quad->ShouldDrawWithBlending() ||
                   !IsDefaultBlendMode(blend_mode)));
  if (!params->use_shaders_for_blending) {
    if (!use_blend_equation_advanced_coherent_ && use_blend_equation_advanced_)
      gl_->BlendBarrierKHR();

    ApplyBlendModeUsingBlendFunc(blend_mode);
  }
}

void GLRenderer::ChooseRPDQProgram(DrawRenderPassDrawQuadParams* params,
                                   const gfx::ColorSpace& target_color_space) {
  TexCoordPrecision tex_coord_precision = TexCoordPrecisionRequired(
      gl_, &highp_threshold_cache_, settings_->highp_threshold_min,
      params->quad->shared_quad_state->visible_quad_layer_rect.size());

  BlendMode shader_blend_mode =
      params->use_shaders_for_blending
          ? BlendModeFromSkXfermode(params->quad->shared_quad_state->blend_mode)
          : BLEND_MODE_NONE;

  SamplerType sampler_type = SAMPLER_TYPE_2D;
  MaskMode mask_mode = NO_MASK;
  bool mask_for_background = params->mask_for_background;
  if (params->mask_resource_lock) {
    mask_mode = HAS_MASK;
    sampler_type =
        SamplerTypeFromTextureTarget(params->mask_resource_lock->target());
  }
  SetUseProgram(
      ProgramKey::RenderPass(
          tex_coord_precision, sampler_type, shader_blend_mode,
          params->use_aa ? USE_AA : NO_AA, mask_mode, mask_for_background,
          params->use_color_matrix, tint_gl_composited_content_),
      params->contents_and_bypass_color_space, target_color_space);
}

void GLRenderer::UpdateRPDQUniforms(DrawRenderPassDrawQuadParams* params) {
  gfx::RectF tex_rect = params->tex_coord_rect;

  gfx::Size texture_size;
  if (params->filter_image) {
    texture_size.set_width(params->filter_image->width());
    texture_size.set_height(params->filter_image->height());
  } else if (params->contents_texture) {
    texture_size = params->contents_texture->size();
  } else {
    texture_size = params->bypass_quad_texture.size;
  }

  tex_rect.Scale(1.0f / texture_size.width(), 1.0f / texture_size.height());

  DCHECK(current_program_->vertex_tex_transform_location() != -1 ||
         IsContextLost());
  if (params->source_needs_flip) {
    // Flip the content vertically in the shader, as the RenderPass input
    // texture is already oriented the same way as the framebuffer, but the
    // projection transform does a flip.
    gl_->Uniform4f(current_program_->vertex_tex_transform_location(),
                   tex_rect.x(), 1.0f - tex_rect.y(), tex_rect.width(),
                   -tex_rect.height());
  } else {
    // Tile textures are oriented opposite the framebuffer, so can use
    // the projection transform to do the flip.
    gl_->Uniform4f(current_program_->vertex_tex_transform_location(),
                   tex_rect.x(), tex_rect.y(), tex_rect.width(),
                   tex_rect.height());
  }

  GLint last_texture_unit = 0;
  if (current_program_->mask_sampler_location() != -1) {
    DCHECK(params->mask_resource_lock);
    DCHECK_NE(current_program_->mask_tex_coord_scale_location(), 1);
    DCHECK_NE(current_program_->mask_tex_coord_offset_location(), 1);
    gl_->Uniform1i(current_program_->mask_sampler_location(), 1);

    gfx::RectF mask_uv_rect = params->quad->mask_uv_rect;
    if (SamplerTypeFromTextureTarget(params->mask_resource_lock->target()) !=
        SAMPLER_TYPE_2D) {
      mask_uv_rect.Scale(params->quad->mask_texture_size.width(),
                         params->quad->mask_texture_size.height());
    }

    SkMatrix tex_to_mask = SkMatrix::MakeRectToRect(RectFToSkRect(tex_rect),
                                                    RectFToSkRect(mask_uv_rect),
                                                    SkMatrix::kFill_ScaleToFit);

    if (params->source_needs_flip) {
      // Mask textures are oriented vertically flipped relative to the
      // framebuffer and the RenderPass contents texture, so we flip the tex
      // coords from the RenderPass texture to find the mask texture coords.
      tex_to_mask.preTranslate(0, 1);
      tex_to_mask.preScale(1, -1);
    }

    gl_->Uniform2f(current_program_->mask_tex_coord_offset_location(),
                   tex_to_mask.getTranslateX(), tex_to_mask.getTranslateY());
    gl_->Uniform2f(current_program_->mask_tex_coord_scale_location(),
                   tex_to_mask.getScaleX(), tex_to_mask.getScaleY());
    last_texture_unit = 1;
  }

  if (current_program_->edge_location() != -1)
    gl_->Uniform3fv(current_program_->edge_location(), 8, params->edge);

  if (current_program_->color_matrix_location() != -1) {
    float matrix[16];
    for (int i = 0; i < 4; ++i) {
      for (int j = 0; j < 4; ++j)
        matrix[i * 4 + j] = SkScalarToFloat(params->color_matrix[j * 5 + i]);
    }
    gl_->UniformMatrix4fv(current_program_->color_matrix_location(), 1, false,
                          matrix);
  }

  static const float kScale = 1.0f / 255.0f;
  if (current_program_->color_offset_location() != -1) {
    float offset[4];
    for (int i = 0; i < 4; ++i)
      offset[i] = SkScalarToFloat(params->color_matrix[i * 5 + 4]) * kScale;

    gl_->Uniform4fv(current_program_->color_offset_location(), 1, offset);
  }

  if (current_program_->tint_color_matrix_location() != -1) {
    auto matrix = cc::DebugColors::TintCompositedContentColorTransformMatrix();
    gl_->UniformMatrix4fv(current_program_->tint_color_matrix_location(), 1,
                          false, matrix.data());
  }

  if (current_program_->backdrop_location() != -1) {
    DCHECK(params->background_texture || params->background_image_id);
    DCHECK_NE(current_program_->backdrop_location(), 0);
    DCHECK_NE(current_program_->backdrop_rect_location(), 0);

    ++last_texture_unit;
    gl_->Uniform1i(current_program_->backdrop_location(), last_texture_unit);

    gl_->Uniform4f(current_program_->backdrop_rect_location(),
                   params->background_rect.x(), params->background_rect.y(),
                   1.0f / params->background_rect.width(),
                   1.0f / params->background_rect.height());

    // Either |background_image_id| or |background_texture| will be the
    // |backdrop_location| in the shader.
    if (params->background_image_id) {
      gl_->ActiveTexture(GL_TEXTURE0 + last_texture_unit);
      gl_->BindTexture(GL_TEXTURE_2D, params->background_image_id);
      gl_->ActiveTexture(GL_TEXTURE0);
    }
    // If |mask_for_background| then we have both |background_image_id| and
    // |background_texture|, and the latter will be the
    // |original_backdrop_location| in the shader.
    if (params->mask_for_background) {
      DCHECK(params->background_image_id);
      DCHECK(params->background_texture);
      ++last_texture_unit;
      gl_->Uniform1i(current_program_->original_backdrop_location(),
                     last_texture_unit);
    }
    if (params->background_texture) {
      gl_->ActiveTexture(GL_TEXTURE0 + last_texture_unit);
      gl_->BindTexture(GL_TEXTURE_2D, params->background_texture);
      gl_->ActiveTexture(GL_TEXTURE0);
    }
  }

  SetShaderOpacity(params->quad->shared_quad_state->opacity);
  SetShaderQuadF(params->surface_quad);
}

void GLRenderer::DrawRPDQ(const DrawRenderPassDrawQuadParams& params) {
  DrawQuadGeometry(params.projection_matrix, params.quad_to_target_transform,
                   params.dst_rect);

  // Flush the compositor context before the filter bitmap goes out of
  // scope, so the draw gets processed before the filter texture gets deleted.
  if (params.filter_image)
    gl_->Flush();

  if (!params.use_shaders_for_blending)
    RestoreBlendFuncToDefault(params.quad->shared_quad_state->blend_mode);
}

namespace {
// These functions determine if a quad, clipped by a clip_region contains
// the entire {top|bottom|left|right} edge.
bool is_top(const gfx::QuadF* clip_region, const DrawQuad* quad) {
  if (!quad->IsTopEdge())
    return false;
  if (!clip_region)
    return true;

  return std::abs(clip_region->p1().y()) < kAntiAliasingEpsilon &&
         std::abs(clip_region->p2().y()) < kAntiAliasingEpsilon;
}

bool is_bottom(const gfx::QuadF* clip_region, const DrawQuad* quad) {
  if (!quad->IsBottomEdge())
    return false;
  if (!clip_region)
    return true;

  return std::abs(clip_region->p3().y() -
                  quad->shared_quad_state->quad_layer_rect.height()) <
             kAntiAliasingEpsilon &&
         std::abs(clip_region->p4().y() -
                  quad->shared_quad_state->quad_layer_rect.height()) <
             kAntiAliasingEpsilon;
}

bool is_left(const gfx::QuadF* clip_region, const DrawQuad* quad) {
  if (!quad->IsLeftEdge())
    return false;
  if (!clip_region)
    return true;

  return std::abs(clip_region->p1().x()) < kAntiAliasingEpsilon &&
         std::abs(clip_region->p4().x()) < kAntiAliasingEpsilon;
}

bool is_right(const gfx::QuadF* clip_region, const DrawQuad* quad) {
  if (!quad->IsRightEdge())
    return false;
  if (!clip_region)
    return true;

  return std::abs(clip_region->p2().x() -
                  quad->shared_quad_state->quad_layer_rect.width()) <
             kAntiAliasingEpsilon &&
         std::abs(clip_region->p3().x() -
                  quad->shared_quad_state->quad_layer_rect.width()) <
             kAntiAliasingEpsilon;
}
}  // anonymous namespace

static gfx::QuadF GetDeviceQuadWithAntialiasingOnExteriorEdges(
    const LayerQuad& device_layer_edges,
    const gfx::Transform& device_transform,
    const gfx::QuadF& tile_quad,
    const gfx::QuadF* clip_region,
    const DrawQuad* quad) {
  auto tile_rect = gfx::RectF(quad->visible_rect);

  gfx::PointF bottom_right = tile_quad.p3();
  gfx::PointF bottom_left = tile_quad.p4();
  gfx::PointF top_left = tile_quad.p1();
  gfx::PointF top_right = tile_quad.p2();
  bool clipped = false;

  // Map points to device space. We ignore |clipped|, since the result of
  // |MapPoint()| still produces a valid point to draw the quad with. When
  // clipped, the point will be outside of the viewport. See crbug.com/416367.
  bottom_right =
      cc::MathUtil::MapPoint(device_transform, bottom_right, &clipped);
  bottom_left = cc::MathUtil::MapPoint(device_transform, bottom_left, &clipped);
  top_left = cc::MathUtil::MapPoint(device_transform, top_left, &clipped);
  top_right = cc::MathUtil::MapPoint(device_transform, top_right, &clipped);

  LayerQuad::Edge bottom_edge(bottom_right, bottom_left);
  LayerQuad::Edge left_edge(bottom_left, top_left);
  LayerQuad::Edge top_edge(top_left, top_right);
  LayerQuad::Edge right_edge(top_right, bottom_right);

  // Only apply anti-aliasing to edges not clipped by culling or scissoring.
  // If an edge is degenerate we do not want to replace it with a "proper" edge
  // as that will cause the quad to possibly expand in strange ways.
  if (!top_edge.degenerate() && is_top(clip_region, quad) &&
      tile_rect.y() == quad->rect.y()) {
    top_edge = device_layer_edges.top();
  }
  if (!left_edge.degenerate() && is_left(clip_region, quad) &&
      tile_rect.x() == quad->rect.x()) {
    left_edge = device_layer_edges.left();
  }
  if (!right_edge.degenerate() && is_right(clip_region, quad) &&
      tile_rect.right() == quad->rect.right()) {
    right_edge = device_layer_edges.right();
  }
  if (!bottom_edge.degenerate() && is_bottom(clip_region, quad) &&
      tile_rect.bottom() == quad->rect.bottom()) {
    bottom_edge = device_layer_edges.bottom();
  }

  float sign = tile_quad.IsCounterClockwise() ? -1 : 1;
  bottom_edge.scale(sign);
  left_edge.scale(sign);
  top_edge.scale(sign);
  right_edge.scale(sign);

  // Create device space quad.
  return LayerQuad(left_edge, top_edge, right_edge, bottom_edge).ToQuadF();
}

float GetTotalQuadError(const gfx::QuadF* clipped_quad,
                        const gfx::QuadF* ideal_rect) {
  return (clipped_quad->p1() - ideal_rect->p1()).LengthSquared() +
         (clipped_quad->p2() - ideal_rect->p2()).LengthSquared() +
         (clipped_quad->p3() - ideal_rect->p3()).LengthSquared() +
         (clipped_quad->p4() - ideal_rect->p4()).LengthSquared();
}

// Attempt to rotate the clipped quad until it lines up the most
// correctly. This is necessary because we check the edges of this
// quad against the expected left/right/top/bottom for anti-aliasing.
void AlignQuadToBoundingBox(gfx::QuadF* clipped_quad) {
  auto bounding_quad = gfx::QuadF(clipped_quad->BoundingBox());
  gfx::QuadF best_rotation = *clipped_quad;
  float least_error_amount = GetTotalQuadError(clipped_quad, &bounding_quad);
  for (size_t i = 1; i < 4; ++i) {
    clipped_quad->Realign(1);
    float new_error = GetTotalQuadError(clipped_quad, &bounding_quad);
    if (new_error < least_error_amount) {
      least_error_amount = new_error;
      best_rotation = *clipped_quad;
    }
  }
  *clipped_quad = best_rotation;
}

void InflateAntiAliasingDistances(const gfx::QuadF& quad,
                                  LayerQuad* device_layer_edges,
                                  float edge[24]) {
  DCHECK(!quad.BoundingBox().IsEmpty());
  LayerQuad device_layer_bounds(gfx::QuadF(quad.BoundingBox()));

  device_layer_edges->InflateAntiAliasingDistance();
  device_layer_edges->ToFloatArray(edge);

  device_layer_bounds.InflateAntiAliasingDistance();
  device_layer_bounds.ToFloatArray(&edge[12]);
}

// static
bool GLRenderer::ShouldAntialiasQuad(const gfx::QuadF& device_layer_quad,
                                     bool clipped,
                                     bool force_aa) {
  // AAing clipped quads is not supported by the code yet.
  if (clipped)
    return false;
  if (device_layer_quad.BoundingBox().IsEmpty())
    return false;
  if (force_aa)
    return true;

  bool is_axis_aligned_in_target = device_layer_quad.IsRectilinear();
  bool is_nearest_rect_within_epsilon =
      is_axis_aligned_in_target &&
      gfx::IsNearestRectWithinDistance(device_layer_quad.BoundingBox(),
                                       kAntiAliasingEpsilon);
  return !is_nearest_rect_within_epsilon;
}

// static
void GLRenderer::SetupQuadForClippingAndAntialiasing(
    const gfx::Transform& device_transform,
    const DrawQuad* quad,
    const gfx::QuadF* aa_quad,
    const gfx::QuadF* clip_region,
    gfx::QuadF* local_quad,
    float edge[24]) {
  gfx::QuadF rotated_clip;
  const gfx::QuadF* local_clip_region = clip_region;
  if (local_clip_region) {
    rotated_clip = *clip_region;
    AlignQuadToBoundingBox(&rotated_clip);
    local_clip_region = &rotated_clip;
  }

  if (!aa_quad) {
    if (local_clip_region)
      *local_quad = *local_clip_region;
    return;
  }

  LayerQuad device_layer_edges(*aa_quad);
  InflateAntiAliasingDistances(*aa_quad, &device_layer_edges, edge);

  // If we have a clip region then we are split, and therefore
  // by necessity, at least one of our edges is not an external
  // one.
  bool is_full_rect = quad->visible_rect == quad->rect;

  bool region_contains_all_outside_edges =
      is_full_rect &&
      (is_top(local_clip_region, quad) && is_left(local_clip_region, quad) &&
       is_bottom(local_clip_region, quad) && is_right(local_clip_region, quad));

  bool use_aa_on_all_four_edges =
      !local_clip_region && region_contains_all_outside_edges;

  gfx::QuadF device_quad;
  if (use_aa_on_all_four_edges) {
    device_quad = device_layer_edges.ToQuadF();
  } else {
    gfx::QuadF tile_quad(local_clip_region
                             ? *local_clip_region
                             : gfx::QuadF(gfx::RectF(quad->visible_rect)));
    device_quad = GetDeviceQuadWithAntialiasingOnExteriorEdges(
        device_layer_edges, device_transform, tile_quad, local_clip_region,
        quad);
  }

  *local_quad =
      cc::MathUtil::InverseMapQuadToLocalSpace(device_transform, device_quad);
}

// static
void GLRenderer::SetupRenderPassQuadForClippingAndAntialiasing(
    const gfx::Transform& device_transform,
    const RenderPassDrawQuad* quad,
    const gfx::QuadF* aa_quad,
    const gfx::QuadF* clip_region,
    gfx::QuadF* local_quad,
    float edge[24]) {
  gfx::QuadF rotated_clip;
  const gfx::QuadF* local_clip_region = clip_region;
  if (local_clip_region) {
    rotated_clip = *clip_region;
    AlignQuadToBoundingBox(&rotated_clip);
    local_clip_region = &rotated_clip;
  }

  if (!aa_quad) {
    GetScaledRegion(quad->rect, local_clip_region, local_quad);
    return;
  }

  LayerQuad device_layer_edges(*aa_quad);
  InflateAntiAliasingDistances(*aa_quad, &device_layer_edges, edge);

  gfx::QuadF device_quad;

  // Apply anti-aliasing only to the edges that are not being clipped
  if (local_clip_region) {
    gfx::QuadF tile_quad(gfx::RectF(quad->visible_rect));
    GetScaledRegion(quad->rect, local_clip_region, &tile_quad);
    device_quad = GetDeviceQuadWithAntialiasingOnExteriorEdges(
        device_layer_edges, device_transform, tile_quad, local_clip_region,
        quad);
  } else {
    device_quad = device_layer_edges.ToQuadF();
  }

  *local_quad =
      cc::MathUtil::InverseMapQuadToLocalSpace(device_transform, device_quad);
}

void GLRenderer::DrawSolidColorQuad(const SolidColorDrawQuad* quad,
                                    const gfx::QuadF* clip_region) {
  gfx::Rect tile_rect = quad->visible_rect;

  SkColor color = quad->color;
  float opacity = quad->shared_quad_state->opacity;
  float alpha = (SkColorGetA(color) * (1.0f / 255.0f)) * opacity;

  // Early out if alpha is small enough that quad doesn't contribute to output.
  if (alpha < std::numeric_limits<float>::epsilon() &&
      quad->ShouldDrawWithBlending() &&
      quad->shared_quad_state->blend_mode == SkBlendMode::kSrcOver)
    return;

  gfx::Transform device_transform =
      current_frame()->window_matrix * current_frame()->projection_matrix *
      quad->shared_quad_state->quad_to_target_transform;
  device_transform.FlattenTo2d();
  if (!device_transform.IsInvertible())
    return;

  auto local_quad = gfx::QuadF(gfx::RectF(tile_rect));

  gfx::QuadF device_layer_quad;
  bool use_aa = false;
  bool allow_aa = settings_->allow_antialiasing &&
                  !quad->force_anti_aliasing_off && quad->IsEdge();

  if (allow_aa) {
    bool clipped = false;
    bool force_aa = false;
    device_layer_quad = cc::MathUtil::MapQuad(
        device_transform,
        gfx::QuadF(
            gfx::RectF(quad->shared_quad_state->visible_quad_layer_rect)),
        &clipped);
    use_aa = ShouldAntialiasQuad(device_layer_quad, clipped, force_aa);
  }

  float edge[24];
  const gfx::QuadF* aa_quad = use_aa ? &device_layer_quad : nullptr;
  SetupQuadForClippingAndAntialiasing(device_transform, quad, aa_quad,
                                      clip_region, &local_quad, edge);

  gfx::ColorSpace quad_color_space = gfx::ColorSpace::CreateSRGB();
  SetUseProgram(ProgramKey::SolidColor(use_aa ? USE_AA : NO_AA,
                                       tint_gl_composited_content_),
                quad_color_space,
                current_frame()->current_render_pass->color_space);
  SetShaderColor(color, opacity);

  if (current_program_->tint_color_matrix_location() != -1) {
    auto matrix = cc::DebugColors::TintCompositedContentColorTransformMatrix();
    gl_->UniformMatrix4fv(current_program_->tint_color_matrix_location(), 1,
                          false, matrix.data());
  }

  if (use_aa) {
    gl_->Uniform3fv(current_program_->edge_location(), 8, edge);
  }

  // Enable blending when the quad properties require it or if we decided
  // to use antialiasing.
  SetBlendEnabled(quad->ShouldDrawWithBlending() || use_aa);
  ApplyBlendModeUsingBlendFunc(quad->shared_quad_state->blend_mode);

  // Antialising requires a normalized quad, but this could lead to floating
  // point precision errors, so only normalize when antialising is on.
  if (use_aa) {
    DrawQuadGeometryWithAA(quad, &local_quad, tile_rect);
  } else {
    PrepareGeometry(SHARED_BINDING);
    SetShaderQuadF(local_quad);
    SetShaderMatrix(current_frame()->projection_matrix *
                    quad->shared_quad_state->quad_to_target_transform);
    gl_->DrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, nullptr);
    num_triangles_drawn_ += 2;
  }
  RestoreBlendFuncToDefault(quad->shared_quad_state->blend_mode);
}

void GLRenderer::DrawTileQuad(const TileDrawQuad* quad,
                              const gfx::QuadF* clip_region) {
  DrawContentQuad(quad, quad->resource_id(), clip_region);
}

void GLRenderer::DrawContentQuad(const ContentDrawQuadBase* quad,
                                 ResourceId resource_id,
                                 const gfx::QuadF* clip_region) {
  gfx::Transform device_transform =
      current_frame()->window_matrix * current_frame()->projection_matrix *
      quad->shared_quad_state->quad_to_target_transform;
  device_transform.FlattenTo2d();

  gfx::QuadF device_layer_quad;
  bool use_aa = false;
  bool allow_aa = settings_->allow_antialiasing &&
                  !quad->force_anti_aliasing_off && quad->IsEdge();
  if (allow_aa) {
    bool clipped = false;
    bool force_aa = false;
    device_layer_quad = cc::MathUtil::MapQuad(
        device_transform,
        gfx::QuadF(
            gfx::RectF(quad->shared_quad_state->visible_quad_layer_rect)),
        &clipped);
    use_aa = ShouldAntialiasQuad(device_layer_quad, clipped, force_aa);
  }

  // TODO(timav): simplify coordinate transformations in DrawContentQuadAA
  // similar to the way DrawContentQuadNoAA works and then consider
  // combining DrawContentQuadAA and DrawContentQuadNoAA into one method.
  if (use_aa)
    DrawContentQuadAA(quad, resource_id, device_transform, device_layer_quad,
                      clip_region);
  else
    DrawContentQuadNoAA(quad, resource_id, clip_region);
}

void GLRenderer::DrawContentQuadAA(const ContentDrawQuadBase* quad,
                                   ResourceId resource_id,
                                   const gfx::Transform& device_transform,
                                   const gfx::QuadF& aa_quad,
                                   const gfx::QuadF* clip_region) {
  if (!device_transform.IsInvertible())
    return;

  gfx::Rect tile_rect = quad->visible_rect;

  gfx::RectF tex_coord_rect = cc::MathUtil::ScaleRectProportional(
      quad->tex_coord_rect, gfx::RectF(quad->rect), gfx::RectF(tile_rect));
  float tex_to_geom_scale_x = quad->rect.width() / quad->tex_coord_rect.width();
  float tex_to_geom_scale_y =
      quad->rect.height() / quad->tex_coord_rect.height();

  gfx::RectF clamp_geom_rect(tile_rect);
  gfx::RectF clamp_tex_rect(tex_coord_rect);
  // Clamp texture coordinates to avoid sampling outside the layer
  // by deflating the tile region half a texel or half a texel
  // minus epsilon for one pixel layers. The resulting clamp region
  // is mapped to the unit square by the vertex shader and mapped
  // back to normalized texture coordinates by the fragment shader
  // after being clamped to 0-1 range.
  float tex_clamp_x =
      std::min(0.5f, 0.5f * clamp_tex_rect.width() - kAntiAliasingEpsilon);
  float tex_clamp_y =
      std::min(0.5f, 0.5f * clamp_tex_rect.height() - kAntiAliasingEpsilon);
  float geom_clamp_x =
      std::min(tex_clamp_x * tex_to_geom_scale_x,
               0.5f * clamp_geom_rect.width() - kAntiAliasingEpsilon);
  float geom_clamp_y =
      std::min(tex_clamp_y * tex_to_geom_scale_y,
               0.5f * clamp_geom_rect.height() - kAntiAliasingEpsilon);
  clamp_geom_rect.Inset(geom_clamp_x, geom_clamp_y, geom_clamp_x, geom_clamp_y);
  clamp_tex_rect.Inset(tex_clamp_x, tex_clamp_y, tex_clamp_x, tex_clamp_y);

  // Map clamping rectangle to unit square.
  float vertex_tex_translate_x = -clamp_geom_rect.x() / clamp_geom_rect.width();
  float vertex_tex_translate_y =
      -clamp_geom_rect.y() / clamp_geom_rect.height();
  float vertex_tex_scale_x = tile_rect.width() / clamp_geom_rect.width();
  float vertex_tex_scale_y = tile_rect.height() / clamp_geom_rect.height();

  TexCoordPrecision tex_coord_precision = TexCoordPrecisionRequired(
      gl_, &highp_threshold_cache_, settings_->highp_threshold_min,
      quad->texture_size);

  auto local_quad = gfx::QuadF(gfx::RectF(tile_rect));
  float edge[24];
  SetupQuadForClippingAndAntialiasing(device_transform, quad, &aa_quad,
                                      clip_region, &local_quad, edge);
  DisplayResourceProvider::ScopedSamplerGL quad_resource_lock(
      resource_provider_, resource_id,
      quad->nearest_neighbor ? GL_NEAREST : GL_LINEAR);
  SamplerType sampler =
      SamplerTypeFromTextureTarget(quad_resource_lock.target());

  float fragment_tex_translate_x = clamp_tex_rect.x();
  float fragment_tex_translate_y = clamp_tex_rect.y();
  float fragment_tex_scale_x = clamp_tex_rect.width();
  float fragment_tex_scale_y = clamp_tex_rect.height();

  // Map to normalized texture coordinates.
  if (sampler != SAMPLER_TYPE_2D_RECT) {
    gfx::Size texture_size = quad->texture_size;
    DCHECK(!texture_size.IsEmpty());
    fragment_tex_translate_x /= texture_size.width();
    fragment_tex_translate_y /= texture_size.height();
    fragment_tex_scale_x /= texture_size.width();
    fragment_tex_scale_y /= texture_size.height();
  }

  SetUseProgram(
      ProgramKey::Tile(tex_coord_precision, sampler, USE_AA,
                       quad->swizzle_contents ? DO_SWIZZLE : NO_SWIZZLE,
                       quad->is_premultiplied ? PREMULTIPLIED_ALPHA
                                              : NON_PREMULTIPLIED_ALPHA,
                       false, false, tint_gl_composited_content_),
      quad_resource_lock.color_space(),
      current_frame()->current_render_pass->color_space);

  if (current_program_->tint_color_matrix_location() != -1) {
    auto matrix = cc::DebugColors::TintCompositedContentColorTransformMatrix();
    gl_->UniformMatrix4fv(current_program_->tint_color_matrix_location(), 1,
                          false, matrix.data());
  }

  gl_->Uniform3fv(current_program_->edge_location(), 8, edge);

  gl_->Uniform4f(current_program_->vertex_tex_transform_location(),
                 vertex_tex_translate_x, vertex_tex_translate_y,
                 vertex_tex_scale_x, vertex_tex_scale_y);
  gl_->Uniform4f(current_program_->fragment_tex_transform_location(),
                 fragment_tex_translate_x, fragment_tex_translate_y,
                 fragment_tex_scale_x, fragment_tex_scale_y);

  // Blending is required for antialiasing.
  SetBlendEnabled(true);
  SetShaderOpacity(quad->shared_quad_state->opacity);

  // Draw the quad with antialiasing.
  DrawQuadGeometryWithAA(quad, &local_quad, tile_rect);
}

void GLRenderer::DrawContentQuadNoAA(const ContentDrawQuadBase* quad,
                                     ResourceId resource_id,
                                     const gfx::QuadF* clip_region) {
  gfx::RectF tex_coord_rect = cc::MathUtil::ScaleRectProportional(
      quad->tex_coord_rect, gfx::RectF(quad->rect),
      gfx::RectF(quad->visible_rect));
  float tex_to_geom_scale_x = quad->rect.width() / quad->tex_coord_rect.width();
  float tex_to_geom_scale_y =
      quad->rect.height() / quad->tex_coord_rect.height();

  bool scaled = (tex_to_geom_scale_x != 1.f || tex_to_geom_scale_y != 1.f);
  GLenum filter = (scaled || !quad->shared_quad_state->quad_to_target_transform
                                  .IsIdentityOrIntegerTranslation()) &&
                          !quad->nearest_neighbor
                      ? GL_LINEAR
                      : GL_NEAREST;

  DisplayResourceProvider::ScopedSamplerGL quad_resource_lock(
      resource_provider_, resource_id, filter);
  SamplerType sampler =
      SamplerTypeFromTextureTarget(quad_resource_lock.target());

  // Tiles are guaranteed to have been entirely filled except for the
  // bottom/right external edge tiles.  Because of border texels, any
  // internal edge will have uvs that are offset from 0 and 1, so
  // clamping to tex_coord_rect in all cases would cause these border
  // texels to not be sampled.  Therefore, only clamp texture coordinates
  // for external edge bottom/right tiles that don't have content all
  // the way to the edge and are using bilinear filtering.
  gfx::Size texture_size = quad->texture_size;
  bool fills_right_edge =
      !quad->IsRightEdge() || texture_size.width() == tex_coord_rect.right();
  bool fills_bottom_edge =
      !quad->IsBottomEdge() || texture_size.height() == tex_coord_rect.bottom();
  bool has_tex_clamp_rect =
      filter == GL_LINEAR && (!fills_right_edge || !fills_bottom_edge);
  gfx::SizeF tex_clamp_size(texture_size);
  // Clamp from the original tex coord rect, instead of the one that has
  // been adjusted by the visible rect.
  if (!fills_right_edge)
    tex_clamp_size.set_width(quad->tex_coord_rect.right() - 0.5f);
  if (!fills_bottom_edge)
    tex_clamp_size.set_height(quad->tex_coord_rect.bottom() - 0.5f);

  // Map to normalized texture coordinates.
  if (sampler != SAMPLER_TYPE_2D_RECT) {
    DCHECK(!texture_size.IsEmpty());
    tex_coord_rect.Scale(1.f / texture_size.width(),
                         1.f / texture_size.height());
    tex_clamp_size.Scale(1.f / texture_size.width(),
                         1.f / texture_size.height());
  }

  TexCoordPrecision tex_coord_precision =
      TexCoordPrecisionRequired(gl_, &highp_threshold_cache_,
                                settings_->highp_threshold_min, texture_size);
  SetUseProgram(
      ProgramKey::Tile(tex_coord_precision, sampler, NO_AA,
                       quad->swizzle_contents ? DO_SWIZZLE : NO_SWIZZLE,
                       quad->is_premultiplied ? PREMULTIPLIED_ALPHA
                                              : NON_PREMULTIPLIED_ALPHA,
                       !quad->ShouldDrawWithBlending(), has_tex_clamp_rect,
                       tint_gl_composited_content_),
      quad_resource_lock.color_space(),
      current_frame()->current_render_pass->color_space);

  if (current_program_->tint_color_matrix_location() != -1) {
    auto matrix = cc::DebugColors::TintCompositedContentColorTransformMatrix();
    gl_->UniformMatrix4fv(current_program_->tint_color_matrix_location(), 1,
                          false, matrix.data());
  }

  if (has_tex_clamp_rect) {
    gl_->Uniform4f(current_program_->tex_clamp_rect_location(), 0, 0,
                   tex_clamp_size.width(), tex_clamp_size.height());
  }
  gl_->Uniform4f(current_program_->vertex_tex_transform_location(),
                 tex_coord_rect.x(), tex_coord_rect.y(), tex_coord_rect.width(),
                 tex_coord_rect.height());

  SetBlendEnabled(quad->ShouldDrawWithBlending());

  SetShaderOpacity(quad->shared_quad_state->opacity);

  // Pass quad coordinates to the uniform in the same order as GeometryBinding
  // does, then vertices will match the texture mapping in the vertex buffer.
  // The method SetShaderQuadF() changes the order of vertices and so it's
  // not used here.
  auto tile_quad = gfx::QuadF(gfx::RectF(quad->visible_rect));
  float width = quad->visible_rect.width();
  float height = quad->visible_rect.height();
  auto top_left = gfx::PointF(quad->visible_rect.origin());
  if (clip_region) {
    tile_quad = *clip_region;
    float gl_uv[8] = {
        (tile_quad.p4().x() - top_left.x()) / width,
        (tile_quad.p4().y() - top_left.y()) / height,
        (tile_quad.p1().x() - top_left.x()) / width,
        (tile_quad.p1().y() - top_left.y()) / height,
        (tile_quad.p2().x() - top_left.x()) / width,
        (tile_quad.p2().y() - top_left.y()) / height,
        (tile_quad.p3().x() - top_left.x()) / width,
        (tile_quad.p3().y() - top_left.y()) / height,
    };
    PrepareGeometry(CLIPPED_BINDING);
    clipped_geometry_->InitializeCustomQuadWithUVs(
        gfx::QuadF(gfx::RectF(quad->visible_rect)), gl_uv);
  } else {
    PrepareGeometry(SHARED_BINDING);
  }
  float gl_quad[8] = {
      tile_quad.p4().x(), tile_quad.p4().y(), tile_quad.p1().x(),
      tile_quad.p1().y(), tile_quad.p2().x(), tile_quad.p2().y(),
      tile_quad.p3().x(), tile_quad.p3().y(),
  };
  gl_->Uniform2fv(current_program_->quad_location(), 4, gl_quad);

  SetShaderMatrix(current_frame()->projection_matrix *
                  quad->shared_quad_state->quad_to_target_transform);

  gl_->DrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, nullptr);
  num_triangles_drawn_ += 2;
}

void GLRenderer::DrawYUVVideoQuad(const YUVVideoDrawQuad* quad,
                                  const gfx::QuadF* clip_region) {
  SetBlendEnabled(quad->ShouldDrawWithBlending());

  TexCoordPrecision tex_coord_precision = TexCoordPrecisionRequired(
      gl_, &highp_threshold_cache_, settings_->highp_threshold_min,
      quad->shared_quad_state->visible_quad_layer_rect.size());
  YUVAlphaTextureMode alpha_texture_mode = quad->a_plane_resource_id()
                                               ? YUV_HAS_ALPHA_TEXTURE
                                               : YUV_NO_ALPHA_TEXTURE;
  UVTextureMode uv_texture_mode =
      quad->v_plane_resource_id() == quad->u_plane_resource_id()
          ? UV_TEXTURE_MODE_UV
          : UV_TEXTURE_MODE_U_V;

  DisplayResourceProvider::ScopedSamplerGL y_plane_lock(
      resource_provider_, quad->y_plane_resource_id(), GL_TEXTURE1, GL_LINEAR);
  DisplayResourceProvider::ScopedSamplerGL u_plane_lock(
      resource_provider_, quad->u_plane_resource_id(), GL_TEXTURE2, GL_LINEAR);
  DCHECK_EQ(y_plane_lock.target(), u_plane_lock.target());
  DCHECK_EQ(y_plane_lock.color_space(), u_plane_lock.color_space());

  // TODO(ccameron): There are currently three sources of the color space: the
  // resource, quad->color_space, and quad->video_color_space. Remove two of
  // them.
  gfx::ColorSpace src_color_space = quad->video_color_space;
  // Invalid or unspecified color spaces should be treated as REC709.
  if (!src_color_space.IsValid())
    src_color_space = gfx::ColorSpace::CreateREC709();
  else
    DCHECK_EQ(src_color_space, y_plane_lock.color_space());
  // The source color space should never be RGB.
  DCHECK_NE(src_color_space, src_color_space.GetAsFullRangeRGB());

  gfx::ColorSpace dst_color_space =
      current_frame()->current_render_pass->color_space;
  // Force sRGB output on Windows for overlay candidate video quads to match
  // DirectComposition behavior in case these switch between overlays and
  // compositing. See https://crbug.com/811118 for details.
  if (supports_dc_layers_ &&
      resource_provider_->IsOverlayCandidate(quad->y_plane_resource_id())) {
    DCHECK(resource_provider_->IsOverlayCandidate(quad->u_plane_resource_id()));
    dst_color_space = gfx::ColorSpace::CreateSRGB();
  }

  // TODO(jbauman): Use base::Optional when available.
  std::unique_ptr<DisplayResourceProvider::ScopedSamplerGL> v_plane_lock;
  if (uv_texture_mode == UV_TEXTURE_MODE_U_V) {
    v_plane_lock.reset(new DisplayResourceProvider::ScopedSamplerGL(
        resource_provider_, quad->v_plane_resource_id(), GL_TEXTURE3,
        GL_LINEAR));
    DCHECK_EQ(y_plane_lock.target(), v_plane_lock->target());
    DCHECK_EQ(y_plane_lock.color_space(), v_plane_lock->color_space());
  }
  std::unique_ptr<DisplayResourceProvider::ScopedSamplerGL> a_plane_lock;
  if (alpha_texture_mode == YUV_HAS_ALPHA_TEXTURE) {
    a_plane_lock.reset(new DisplayResourceProvider::ScopedSamplerGL(
        resource_provider_, quad->a_plane_resource_id(), GL_TEXTURE4,
        GL_LINEAR));
    DCHECK_EQ(y_plane_lock.target(), a_plane_lock->target());
  }

  // All planes must have the same sampler type.
  SamplerType sampler = SamplerTypeFromTextureTarget(y_plane_lock.target());

  SetUseProgram(
      ProgramKey::YUVVideo(tex_coord_precision, sampler, alpha_texture_mode,
                           uv_texture_mode, tint_gl_composited_content_),
      src_color_space, dst_color_space);

  if (current_program_->tint_color_matrix_location() != -1) {
    auto matrix = cc::DebugColors::TintCompositedContentColorTransformMatrix();
    gl_->UniformMatrix4fv(current_program_->tint_color_matrix_location(), 1,
                          false, matrix.data());
  }

  gfx::SizeF ya_tex_scale(1.0f, 1.0f);
  gfx::SizeF uv_tex_scale(1.0f, 1.0f);
  if (sampler != SAMPLER_TYPE_2D_RECT) {
    DCHECK(!quad->ya_tex_size.IsEmpty());
    DCHECK(!quad->uv_tex_size.IsEmpty());
    ya_tex_scale = gfx::SizeF(1.0f / quad->ya_tex_size.width(),
                              1.0f / quad->ya_tex_size.height());
    uv_tex_scale = gfx::SizeF(1.0f / quad->uv_tex_size.width(),
                              1.0f / quad->uv_tex_size.height());
  }

  float ya_vertex_tex_translate_x =
      quad->ya_tex_coord_rect.x() * ya_tex_scale.width();
  float ya_vertex_tex_translate_y =
      quad->ya_tex_coord_rect.y() * ya_tex_scale.height();
  float ya_vertex_tex_scale_x =
      quad->ya_tex_coord_rect.width() * ya_tex_scale.width();
  float ya_vertex_tex_scale_y =
      quad->ya_tex_coord_rect.height() * ya_tex_scale.height();

  float uv_vertex_tex_translate_x =
      quad->uv_tex_coord_rect.x() * uv_tex_scale.width();
  float uv_vertex_tex_translate_y =
      quad->uv_tex_coord_rect.y() * uv_tex_scale.height();
  float uv_vertex_tex_scale_x =
      quad->uv_tex_coord_rect.width() * uv_tex_scale.width();
  float uv_vertex_tex_scale_y =
      quad->uv_tex_coord_rect.height() * uv_tex_scale.height();

  gl_->Uniform2f(current_program_->ya_tex_scale_location(),
                 ya_vertex_tex_scale_x, ya_vertex_tex_scale_y);
  gl_->Uniform2f(current_program_->ya_tex_offset_location(),
                 ya_vertex_tex_translate_x, ya_vertex_tex_translate_y);
  gl_->Uniform2f(current_program_->uv_tex_scale_location(),
                 uv_vertex_tex_scale_x, uv_vertex_tex_scale_y);
  gl_->Uniform2f(current_program_->uv_tex_offset_location(),
                 uv_vertex_tex_translate_x, uv_vertex_tex_translate_y);

  gfx::RectF ya_clamp_rect(ya_vertex_tex_translate_x, ya_vertex_tex_translate_y,
                           ya_vertex_tex_scale_x, ya_vertex_tex_scale_y);
  ya_clamp_rect.Inset(0.5f * ya_tex_scale.width(),
                      0.5f * ya_tex_scale.height());
  gfx::RectF uv_clamp_rect(uv_vertex_tex_translate_x, uv_vertex_tex_translate_y,
                           uv_vertex_tex_scale_x, uv_vertex_tex_scale_y);
  uv_clamp_rect.Inset(0.5f * uv_tex_scale.width(),
                      0.5f * uv_tex_scale.height());
  gl_->Uniform4f(current_program_->ya_clamp_rect_location(), ya_clamp_rect.x(),
                 ya_clamp_rect.y(), ya_clamp_rect.right(),
                 ya_clamp_rect.bottom());
  gl_->Uniform4f(current_program_->uv_clamp_rect_location(), uv_clamp_rect.x(),
                 uv_clamp_rect.y(), uv_clamp_rect.right(),
                 uv_clamp_rect.bottom());

  gl_->Uniform1i(current_program_->y_texture_location(), 1);
  if (uv_texture_mode == UV_TEXTURE_MODE_UV) {
    gl_->Uniform1i(current_program_->uv_texture_location(), 2);
  } else {
    gl_->Uniform1i(current_program_->u_texture_location(), 2);
    gl_->Uniform1i(current_program_->v_texture_location(), 3);
  }
  if (alpha_texture_mode == YUV_HAS_ALPHA_TEXTURE)
    gl_->Uniform1i(current_program_->a_texture_location(), 4);

  gl_->Uniform1f(current_program_->resource_multiplier_location(),
                 quad->resource_multiplier);
  gl_->Uniform1f(current_program_->resource_offset_location(),
                 quad->resource_offset);

  // The transform and vertex data are used to figure out the extents that the
  // un-antialiased quad should have and which vertex this is and the float
  // quad passed in via uniform is the actual geometry that gets used to draw
  // it. This is why this centered rect is used and not the original quad_rect.
  auto tile_rect = gfx::RectF(quad->rect);

  SetShaderOpacity(quad->shared_quad_state->opacity);
  if (!clip_region) {
    DrawQuadGeometry(current_frame()->projection_matrix,
                     quad->shared_quad_state->quad_to_target_transform,
                     tile_rect);
  } else {
    float uvs[8] = {0};
    GetScaledUVs(quad->visible_rect, clip_region, uvs);
    gfx::QuadF region_quad = *clip_region;
    region_quad.Scale(1.0f / tile_rect.width(), 1.0f / tile_rect.height());
    region_quad -= gfx::Vector2dF(0.5f, 0.5f);
    DrawQuadGeometryClippedByQuadF(
        quad->shared_quad_state->quad_to_target_transform, tile_rect,
        region_quad, uvs);
  }
}

void GLRenderer::DrawStreamVideoQuad(const StreamVideoDrawQuad* quad,
                                     const gfx::QuadF* clip_region) {
  SetBlendEnabled(quad->ShouldDrawWithBlending());

  DCHECK(output_surface_->context_provider()
             ->ContextCapabilities()
             .egl_image_external);

  TexCoordPrecision tex_coord_precision = TexCoordPrecisionRequired(
      gl_, &highp_threshold_cache_, settings_->highp_threshold_min,
      quad->shared_quad_state->visible_quad_layer_rect.size());

  DisplayResourceProvider::ScopedReadLockGL lock(resource_provider_,
                                                 quad->resource_id());

  SetUseProgram(ProgramKey::VideoStream(tex_coord_precision),
                lock.color_space(),
                current_frame()->current_render_pass->color_space);

  DCHECK_EQ(GL_TEXTURE0, GetActiveTextureUnit(gl_));
  gl_->BindTexture(GL_TEXTURE_EXTERNAL_OES, lock.texture_id());

  static float gl_matrix[16];
  ToGLMatrix(&gl_matrix[0], quad->matrix);
  gl_->UniformMatrix4fvStreamTextureMatrixCHROMIUM(
      current_program_->tex_matrix_location(), false, gl_matrix);

  SetShaderOpacity(quad->shared_quad_state->opacity);
  gfx::Size texture_size = lock.size();
  gfx::Vector2dF uv = quad->matrix.Scale2d();
  gfx::RectF uv_visible_rect(0, 0, uv.x(), uv.y());
  const SamplerType sampler = SamplerTypeFromTextureTarget(lock.target());
  Float4 tex_clamp_rect = UVClampRect(uv_visible_rect, texture_size, sampler);
  gl_->Uniform4f(current_program_->tex_clamp_rect_location(),
                 tex_clamp_rect.data[0], tex_clamp_rect.data[1],
                 tex_clamp_rect.data[2], tex_clamp_rect.data[3]);

  if (!clip_region) {
    DrawQuadGeometry(current_frame()->projection_matrix,
                     quad->shared_quad_state->quad_to_target_transform,
                     gfx::RectF(quad->rect));
  } else {
    gfx::QuadF region_quad(*clip_region);
    region_quad.Scale(1.0f / quad->rect.width(), 1.0f / quad->rect.height());
    region_quad -= gfx::Vector2dF(0.5f, 0.5f);
    float uvs[8] = {0};
    GetScaledUVs(quad->visible_rect, clip_region, uvs);
    DrawQuadGeometryClippedByQuadF(
        quad->shared_quad_state->quad_to_target_transform,
        gfx::RectF(quad->rect), region_quad, uvs);
  }
}

void GLRenderer::FlushTextureQuadCache(BoundGeometry flush_binding) {
  // Check to see if we have anything to draw.
  if (draw_cache_.is_empty)
    return;

  PrepareGeometry(flush_binding);

  // Set the correct blending mode.
  SetBlendEnabled(draw_cache_.needs_blending);

  // Assume the current active textures is 0.
  DisplayResourceProvider::ScopedSamplerGL locked_quad(
      resource_provider_, draw_cache_.resource_id,
      draw_cache_.nearest_neighbor ? GL_NEAREST : GL_LINEAR);

  // Bind the program to the GL state.
  SetUseProgram(draw_cache_.program_key, locked_quad.color_space(),
                current_frame()->current_render_pass->color_space);

  DCHECK_EQ(GL_TEXTURE0, GetActiveTextureUnit(gl_));
  gl_->BindTexture(locked_quad.target(), locked_quad.texture_id());

  static_assert(sizeof(Float4) == 4 * sizeof(float),
                "Float4 struct should be densely packed");
  static_assert(sizeof(Float16) == 16 * sizeof(float),
                "Float16 struct should be densely packed");

  // Upload the tranforms for both points and uvs.
  gl_->UniformMatrix4fv(
      current_program_->matrix_location(),
      static_cast<int>(draw_cache_.matrix_data.size()), false,
      reinterpret_cast<float*>(&draw_cache_.matrix_data.front()));
  gl_->Uniform4fv(current_program_->vertex_tex_transform_location(),
                  static_cast<int>(draw_cache_.uv_xform_data.size()),
                  reinterpret_cast<float*>(&draw_cache_.uv_xform_data.front()));

  if (current_program_->tint_color_matrix_location() != -1) {
    auto matrix = cc::DebugColors::TintCompositedContentColorTransformMatrix();
    gl_->UniformMatrix4fv(current_program_->tint_color_matrix_location(), 1,
                          false, matrix.data());
  }

  if (current_program_->tex_clamp_rect_location() != -1) {
    // Draw batching is not allowed with texture clamping.
    DCHECK_EQ(1u, draw_cache_.matrix_data.size());
    gl_->Uniform4f(current_program_->tex_clamp_rect_location(),
                   draw_cache_.tex_clamp_rect_data.data[0],
                   draw_cache_.tex_clamp_rect_data.data[1],
                   draw_cache_.tex_clamp_rect_data.data[2],
                   draw_cache_.tex_clamp_rect_data.data[3]);
  }

  if (draw_cache_.background_color != SK_ColorTRANSPARENT) {
    Float4 background_color =
        PremultipliedColor(draw_cache_.background_color, 1.f);
    gl_->Uniform4fv(current_program_->background_color_location(), 1,
                    background_color.data);
  }

  gl_->Uniform1fv(
      current_program_->vertex_opacity_location(),
      static_cast<int>(draw_cache_.vertex_opacity_data.size()),
      static_cast<float*>(&draw_cache_.vertex_opacity_data.front()));

  DCHECK_LE(draw_cache_.matrix_data.size(),
            static_cast<size_t>(std::numeric_limits<int>::max()) / 6u);
  // Draw the quads!
  gl_->DrawElements(GL_TRIANGLES,
                    6 * static_cast<int>(draw_cache_.matrix_data.size()),
                    GL_UNSIGNED_SHORT, nullptr);
  num_triangles_drawn_ += 2 * static_cast<int>(draw_cache_.matrix_data.size());

  // Clear the cache.
  draw_cache_.is_empty = true;
  draw_cache_.resource_id = -1;
  draw_cache_.uv_xform_data.resize(0);
  draw_cache_.vertex_opacity_data.resize(0);
  draw_cache_.matrix_data.resize(0);
  draw_cache_.tex_clamp_rect_data = Float4();

  // If we had a clipped binding, prepare the shared binding for the
  // next inserts.
  if (flush_binding == CLIPPED_BINDING) {
    PrepareGeometry(SHARED_BINDING);
  }
}

void GLRenderer::EnqueueTextureQuad(const TextureDrawQuad* quad,
                                    const gfx::QuadF* clip_region) {
  // If we have a clip_region then we have to render the next quad
  // with dynamic geometry, therefore we must flush all pending
  // texture quads.
  if (clip_region) {
    // We send in false here because we want to flush what's currently in the
    // queue using the shared_geometry and not clipped_geometry
    FlushTextureQuadCache(SHARED_BINDING);
  }

  DisplayResourceProvider::ScopedReadLockGL lock(resource_provider_,
                                                 quad->resource_id());
  // ScopedReadLockGL contains the correct texture size, even when
  // quad->resource_size_in_pixesl() is empty.
  const gfx::Size texture_size = lock.size();
  TexCoordPrecision tex_coord_precision =
      TexCoordPrecisionRequired(gl_, &highp_threshold_cache_,
                                settings_->highp_threshold_min, texture_size);

  const SamplerType sampler = SamplerTypeFromTextureTarget(lock.target());

  bool need_tex_clamp_rect = !quad->resource_size_in_pixels().IsEmpty() &&
                             (quad->uv_top_left != gfx::PointF(0, 0) ||
                              quad->uv_bottom_right != gfx::PointF(1, 1));
  ProgramKey program_key = ProgramKey::Texture(
      tex_coord_precision, sampler,
      quad->premultiplied_alpha ? PREMULTIPLIED_ALPHA : NON_PREMULTIPLIED_ALPHA,
      quad->background_color != SK_ColorTRANSPARENT, need_tex_clamp_rect,
      tint_gl_composited_content_);
  int resource_id = quad->resource_id();

  size_t max_quads = StaticGeometryBinding::NUM_QUADS;
  if (draw_cache_.is_empty || draw_cache_.program_key != program_key ||
      draw_cache_.resource_id != resource_id ||
      draw_cache_.needs_blending != quad->ShouldDrawWithBlending() ||
      draw_cache_.nearest_neighbor != quad->nearest_neighbor ||
      draw_cache_.background_color != quad->background_color ||
      draw_cache_.matrix_data.size() >= max_quads) {
    FlushTextureQuadCache(SHARED_BINDING);
    draw_cache_.is_empty = false;
    draw_cache_.program_key = program_key;
    draw_cache_.resource_id = resource_id;
    draw_cache_.needs_blending = quad->ShouldDrawWithBlending();
    draw_cache_.nearest_neighbor = quad->nearest_neighbor;
    draw_cache_.background_color = quad->background_color;
  }

  // Generate the uv-transform
  Float4 uv_transform = {{0.0f, 0.0f, 1.0f, 1.0f}};
  if (!clip_region)
    uv_transform = UVTransform(quad);
  if (sampler == SAMPLER_TYPE_2D_RECT) {
    // Un-normalize the texture coordiantes for rectangle targets.
    uv_transform.data[0] *= texture_size.width();
    uv_transform.data[2] *= texture_size.width();
    uv_transform.data[1] *= texture_size.height();
    uv_transform.data[3] *= texture_size.height();
  }
  draw_cache_.uv_xform_data.push_back(uv_transform);

  if (need_tex_clamp_rect) {
    DCHECK_EQ(1u, draw_cache_.uv_xform_data.size());
    DCHECK_EQ(texture_size.ToString(),
              quad->resource_size_in_pixels().ToString());
    DCHECK(!texture_size.IsEmpty());
    gfx::RectF uv_visible_rect(
        quad->uv_top_left.x(), quad->uv_top_left.y(),
        quad->uv_bottom_right.x() - quad->uv_top_left.x(),
        quad->uv_bottom_right.y() - quad->uv_top_left.y());
    Float4 tex_clamp_rect = UVClampRect(uv_visible_rect, texture_size, sampler);
    draw_cache_.tex_clamp_rect_data = tex_clamp_rect;
  }

  // Generate the vertex opacity
  const float opacity = quad->shared_quad_state->opacity;
  draw_cache_.vertex_opacity_data.push_back(quad->vertex_opacity[0] * opacity);
  draw_cache_.vertex_opacity_data.push_back(quad->vertex_opacity[1] * opacity);
  draw_cache_.vertex_opacity_data.push_back(quad->vertex_opacity[2] * opacity);
  draw_cache_.vertex_opacity_data.push_back(quad->vertex_opacity[3] * opacity);

  // Generate the transform matrix
  gfx::Transform quad_rect_matrix;
  QuadRectTransform(&quad_rect_matrix,
                    quad->shared_quad_state->quad_to_target_transform,
                    gfx::RectF(quad->rect));
  quad_rect_matrix = current_frame()->projection_matrix * quad_rect_matrix;

  Float16 m;
  quad_rect_matrix.matrix().asColMajorf(m.data);
  draw_cache_.matrix_data.push_back(m);

  if (clip_region) {
    gfx::QuadF scaled_region;
    if (!GetScaledRegion(quad->rect, clip_region, &scaled_region)) {
      scaled_region = SharedGeometryQuad().BoundingBox();
    }
    // Both the scaled region and the SharedGeomtryQuad are in the space
    // -0.5->0.5. We need to move that to the space 0->1.
    float uv[8];
    uv[0] = scaled_region.p1().x() + 0.5f;
    uv[1] = scaled_region.p1().y() + 0.5f;
    uv[2] = scaled_region.p2().x() + 0.5f;
    uv[3] = scaled_region.p2().y() + 0.5f;
    uv[4] = scaled_region.p3().x() + 0.5f;
    uv[5] = scaled_region.p3().y() + 0.5f;
    uv[6] = scaled_region.p4().x() + 0.5f;
    uv[7] = scaled_region.p4().y() + 0.5f;
    PrepareGeometry(CLIPPED_BINDING);
    clipped_geometry_->InitializeCustomQuadWithUVs(scaled_region, uv);
    FlushTextureQuadCache(CLIPPED_BINDING);
  } else if (need_tex_clamp_rect) {
    FlushTextureQuadCache(SHARED_BINDING);
  }
}

void GLRenderer::FinishDrawingFrame() {
  if (use_sync_query_) {
    sync_queries_.EndCurrentFrame();
  }

  swap_buffer_rect_.Union(current_frame()->root_damage_rect);
  if (overdraw_feedback_)
    FlushOverdrawFeedback(swap_buffer_rect_);

  if (use_swap_with_bounds_)
    swap_content_bounds_ = current_frame()->root_content_bounds;

  copier_.FreeUnusedCachedResources();

  current_framebuffer_texture_ = nullptr;

  gl_->Disable(GL_BLEND);
  blend_shadow_ = false;

  ScheduleCALayers();
  ScheduleDCLayers();
  ScheduleOverlays();

  TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("viz.triangles"), "Triangles Drawn",
                 num_triangles_drawn_);
}

void GLRenderer::FinishDrawingQuadList() {
  FlushTextureQuadCache(SHARED_BINDING);
}

void GLRenderer::GenerateMipmap() {
  DCHECK(current_framebuffer_texture_);
  current_framebuffer_texture_->set_generate_mipmap();
}

void GLRenderer::SetEnableDCLayers(bool enable) {
  gl_->SetEnableDCLayersCHROMIUM(enable);
}

bool GLRenderer::FlippedFramebuffer() const {
  if (force_drawing_frame_framebuffer_unflipped_)
    return false;
  if (current_frame()->current_render_pass != current_frame()->root_render_pass)
    return true;
  return FlippedRootFramebuffer();
}

bool GLRenderer::FlippedRootFramebuffer() const {
  // GL is normally flipped, so a flipped output results in an unflipping.
  return !output_surface_->capabilities().flipped_output_surface;
}

void GLRenderer::EnsureScissorTestEnabled() {
  if (is_scissor_enabled_)
    return;

  FlushTextureQuadCache(SHARED_BINDING);
  gl_->Enable(GL_SCISSOR_TEST);
  is_scissor_enabled_ = true;
}

void GLRenderer::EnsureScissorTestDisabled() {
  if (!is_scissor_enabled_)
    return;

  FlushTextureQuadCache(SHARED_BINDING);
  gl_->Disable(GL_SCISSOR_TEST);
  is_scissor_enabled_ = false;
}

void GLRenderer::CopyDrawnRenderPass(
    std::unique_ptr<CopyOutputRequest> request) {
  TRACE_EVENT0("viz", "GLRenderer::CopyDrawnRenderPass");

  if (overdraw_feedback_)
    FlushOverdrawFeedback(current_frame()->current_render_pass->output_rect);

  GLuint framebuffer_texture = 0;
  gfx::Size framebuffer_texture_size;
  if (current_framebuffer_texture_) {
    framebuffer_texture = current_framebuffer_texture_->id();
    framebuffer_texture_size = current_framebuffer_texture_->size();
  }
  copier_.CopyFromTextureOrFramebuffer(
      std::move(request), current_frame()->current_render_pass->output_rect,
      GetFramebufferCopyTextureFormat(), framebuffer_texture,
      framebuffer_texture_size, FlippedFramebuffer(),
      current_frame()->current_render_pass->color_space);

  // The copier modified texture/framebuffer bindings, shader programs, and
  // other GL state; and so this must be restored before continuing.
  RestoreGLState();
}

void GLRenderer::ToGLMatrix(float* gl_matrix, const gfx::Transform& transform) {
  transform.matrix().asColMajorf(gl_matrix);
}

void GLRenderer::SetShaderQuadF(const gfx::QuadF& quad) {
  if (!current_program_ || current_program_->quad_location() == -1)
    return;
  float gl_quad[8];
  gl_quad[0] = quad.p1().x();
  gl_quad[1] = quad.p1().y();
  gl_quad[2] = quad.p2().x();
  gl_quad[3] = quad.p2().y();
  gl_quad[4] = quad.p3().x();
  gl_quad[5] = quad.p3().y();
  gl_quad[6] = quad.p4().x();
  gl_quad[7] = quad.p4().y();
  gl_->Uniform2fv(current_program_->quad_location(), 4, gl_quad);
}

void GLRenderer::SetShaderOpacity(float opacity) {
  if (!current_program_ || current_program_->alpha_location() == -1)
    return;
  gl_->Uniform1f(current_program_->alpha_location(), opacity);
}

void GLRenderer::SetShaderMatrix(const gfx::Transform& transform) {
  if (!current_program_ || current_program_->matrix_location() == -1)
    return;
  float gl_matrix[16];
  ToGLMatrix(gl_matrix, transform);
  gl_->UniformMatrix4fv(current_program_->matrix_location(), 1, false,
                        gl_matrix);
}

void GLRenderer::SetShaderColor(SkColor color, float opacity) {
  if (!current_program_ || current_program_->color_location() == -1)
    return;
  Float4 float_color = PremultipliedColor(color, opacity);
  gl_->Uniform4fv(current_program_->color_location(), 1, float_color.data);
}

void GLRenderer::SetStencilEnabled(bool enabled) {
  if (enabled == stencil_shadow_)
    return;

  if (enabled)
    gl_->Enable(GL_STENCIL_TEST);
  else
    gl_->Disable(GL_STENCIL_TEST);
  stencil_shadow_ = enabled;
}

void GLRenderer::SetBlendEnabled(bool enabled) {
  if (enabled == blend_shadow_)
    return;

  if (enabled)
    gl_->Enable(GL_BLEND);
  else
    gl_->Disable(GL_BLEND);
  blend_shadow_ = enabled;
}

void GLRenderer::DrawQuadGeometryClippedByQuadF(
    const gfx::Transform& draw_transform,
    const gfx::RectF& quad_rect,
    const gfx::QuadF& clipping_region_quad,
    const float* uvs) {
  PrepareGeometry(CLIPPED_BINDING);
  if (uvs) {
    clipped_geometry_->InitializeCustomQuadWithUVs(clipping_region_quad, uvs);
  } else {
    clipped_geometry_->InitializeCustomQuad(clipping_region_quad);
  }
  gfx::Transform quad_rect_matrix;
  QuadRectTransform(&quad_rect_matrix, draw_transform, quad_rect);
  SetShaderMatrix(current_frame()->projection_matrix * quad_rect_matrix);

  gl_->DrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT,
                    reinterpret_cast<const void*>(0));
  num_triangles_drawn_ += 2;
}

void GLRenderer::DrawQuadGeometry(const gfx::Transform& projection_matrix,
                                  const gfx::Transform& draw_transform,
                                  const gfx::RectF& quad_rect) {
  PrepareGeometry(SHARED_BINDING);
  gfx::Transform quad_rect_matrix;
  QuadRectTransform(&quad_rect_matrix, draw_transform, quad_rect);
  SetShaderMatrix(projection_matrix * quad_rect_matrix);

  gl_->DrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, nullptr);
  num_triangles_drawn_ += 2;
}

void GLRenderer::DrawQuadGeometryWithAA(const DrawQuad* quad,
                                        gfx::QuadF* local_quad,
                                        const gfx::Rect& tile_rect) {
  DCHECK(local_quad);
  // Normalize to tile_rect.
  local_quad->Scale(1.0f / tile_rect.width(), 1.0f / tile_rect.height());

  SetShaderQuadF(*local_quad);

  // The transform and vertex data are used to figure out the extents that the
  // un-antialiased quad should have and which vertex this is and the float
  // quad passed in via uniform is the actual geometry that gets used to draw
  // it. This is why this centered rect is used and not the original quad_rect.
  DrawQuadGeometry(current_frame()->projection_matrix,
                   quad->shared_quad_state->quad_to_target_transform,
                   CenteredRect(tile_rect));
}

void GLRenderer::SwapBuffers(std::vector<ui::LatencyInfo> latency_info,
                             bool need_presentation_feedback) {
  DCHECK(visible_);

  TRACE_EVENT0("viz", "GLRenderer::SwapBuffers");
  // We're done! Time to swapbuffers!

  gfx::Size surface_size = surface_size_for_swap_buffers();

  OutputSurfaceFrame output_frame;
  output_frame.latency_info = std::move(latency_info);
  output_frame.size = surface_size;
  output_frame.need_presentation_feedback = need_presentation_feedback;
  if (use_swap_with_bounds_) {
    output_frame.content_bounds = std::move(swap_content_bounds_);
  } else if (use_partial_swap_) {
    // If supported, we can save significant bandwidth by only swapping the
    // damaged/scissored region (clamped to the viewport).
    swap_buffer_rect_.Intersect(gfx::Rect(surface_size));
    int flipped_y_pos_of_rect_bottom = surface_size.height() -
                                       swap_buffer_rect_.y() -
                                       swap_buffer_rect_.height();
    output_frame.sub_buffer_rect =
        gfx::Rect(swap_buffer_rect_.x(),
                  FlippedRootFramebuffer() ? flipped_y_pos_of_rect_bottom
                                           : swap_buffer_rect_.y(),
                  swap_buffer_rect_.width(), swap_buffer_rect_.height());
  } else if (swap_buffer_rect_.IsEmpty() && allow_empty_swap_) {
    output_frame.sub_buffer_rect = swap_buffer_rect_;
  }

  // Record resources from viz clients that have been shipped as overlays to the
  // gpu together.
  swapping_overlay_resources_.push_back(std::move(pending_overlay_resources_));
  pending_overlay_resources_.clear();
  if (settings_->release_overlay_resources_after_gpu_query) {
    // Record RenderPass textures that have been shipped as overlays to the gpu
    // together.
    displayed_overlay_textures_.push_back(
        std::move(awaiting_swap_overlay_textures_));
    awaiting_swap_overlay_textures_.clear();
  } else {
    // If |displayed_overlay_textures_| is appended to in this case then
    // SwapBuffersComplete needs to be extended to handle it.
    DCHECK(awaiting_swap_overlay_textures_.empty());
  }

  output_surface_->SwapBuffers(std::move(output_frame));

  swap_buffer_rect_ = gfx::Rect();
}

void GLRenderer::SwapBuffersComplete() {
  if (settings_->release_overlay_resources_after_gpu_query) {
    // Once a resource has been swap-ACKed, send a query to the GPU process to
    // ask if the resource is no longer being consumed by the system compositor.
    // The response will come with the next swap-ACK.
    if (!swapping_overlay_resources_.empty()) {
      for (OverlayResourceLock& lock : swapping_overlay_resources_.front()) {
        unsigned texture = lock->texture_id();
        if (swapped_and_acked_overlay_resources_.find(texture) ==
            swapped_and_acked_overlay_resources_.end()) {
          swapped_and_acked_overlay_resources_[texture] = std::move(lock);
        }
      }
      swapping_overlay_resources_.pop_front();
    }
    if (!displayed_overlay_textures_.empty()) {
      for (auto& overlay : displayed_overlay_textures_.front())
        awaiting_release_overlay_textures_.push_back(std::move(overlay));
      displayed_overlay_textures_.erase(displayed_overlay_textures_.begin());
    }

    size_t query_texture_count = swapped_and_acked_overlay_resources_.size() +
                                 awaiting_release_overlay_textures_.size();
    if (query_texture_count) {
      std::vector<uint32_t> query_texture_ids;
      query_texture_ids.reserve(query_texture_count);

      for (auto& pair : swapped_and_acked_overlay_resources_)
        query_texture_ids.push_back(pair.first);
      for (auto& overlay : awaiting_release_overlay_textures_)
        query_texture_ids.push_back(overlay->texture.id());

      // We query for *all* outstanding texture ids, even if we previously
      // queried, as we will not hear back about things becoming available
      // until after we query again.
      gl_->ScheduleCALayerInUseQueryCHROMIUM(query_texture_count,
                                             query_texture_ids.data());
    }
  } else {
    // If a query is not needed to release the overlay buffers, we can assume
    // that once a swap buffer has completed we can remove the oldest buffers
    // from the queue, but only once we've swapped another frame afterward.
    if (swapping_overlay_resources_.size() > 1) {
      DisplayResourceProvider::ScopedBatchReturnResources returner(
          resource_provider_);
      swapping_overlay_resources_.pop_front();
    }
    // If |displayed_overlay_textures_| has a non-empty member that means we're
    // sending RenderPassDrawQuads as an overlay. This is only supported for
    // CALayers now, where |release_overlay_resources_after_gpu_query| will be
    // true. In order to support them here, the OverlayTextures would need to
    // move to |awaiting_release_overlay_textures_| and stay there until the
    // ResourceFence that was in use for the frame they were submitted is
    // passed.
    DCHECK(displayed_overlay_textures_.empty());
  }
}

void GLRenderer::DidReceiveTextureInUseResponses(
    const gpu::TextureInUseResponses& responses) {
  DCHECK(settings_->release_overlay_resources_after_gpu_query);
  DisplayResourceProvider::ScopedBatchReturnResources returner(
      resource_provider_);
  for (const gpu::TextureInUseResponse& response : responses) {
    if (response.in_use)
      continue;

    // Returned texture ids may be for resources from clients of the
    // display compositor, in |swapped_and_acked_overlay_resources_|. In that
    // case we remove the lock from the map, allowing them to be returned to the
    // client if the resource has been deleted from the DisplayResourceProvider.
    if (swapped_and_acked_overlay_resources_.erase(response.texture))
      continue;
    // If not, then they would be a RenderPass copy texture, which is held in
    // |awaiting_release_overlay_textures_|. We move it back to the available
    // texture list to use it for the next frame.
    auto it = std::find_if(
        awaiting_release_overlay_textures_.begin(),
        awaiting_release_overlay_textures_.end(),
        [&response](const std::unique_ptr<OverlayTexture>& overlay) {
          return overlay->texture.id() == response.texture;
        });
    if (it != awaiting_release_overlay_textures_.end()) {
      // Mark the OverlayTexture as newly returned to the available set.
      (*it)->frames_waiting_for_reuse = 0;
      available_overlay_textures_.push_back(std::move(*it));
      awaiting_release_overlay_textures_.erase(it);
    }
  }
  color_lut_cache_.Swap();
}

void GLRenderer::BindFramebufferToOutputSurface() {
  current_framebuffer_texture_ = nullptr;
  output_surface_->BindFramebuffer();
  tint_gl_composited_content_ = settings_->tint_gl_composited_content;
  if (overdraw_feedback_) {
    // Output surfaces that require an external stencil test should not allow
    // overdraw feedback by setting |supports_stencil| to false.
    DCHECK(!output_surface_->HasExternalStencilTest());
    SetupOverdrawFeedback();
    SetStencilEnabled(true);
  } else if (output_surface_->HasExternalStencilTest()) {
    output_surface_->ApplyExternalStencil();
    SetStencilEnabled(true);
  } else {
    SetStencilEnabled(false);
  }
}

void GLRenderer::BindFramebufferToTexture(const RenderPassId render_pass_id) {
  tint_gl_composited_content_ = false;
  gl_->BindFramebuffer(GL_FRAMEBUFFER, offscreen_framebuffer_id_);

  auto contents_texture_it = render_pass_textures_.find(render_pass_id);
  current_framebuffer_texture_ = &contents_texture_it->second;
  GLuint texture_id = current_framebuffer_texture_->id();
  DCHECK(texture_id);
  gl_->FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
                            texture_id, 0);
  if (overdraw_feedback_) {
    if (!offscreen_stencil_renderbuffer_id_)
      gl_->GenRenderbuffers(1, &offscreen_stencil_renderbuffer_id_);
    if (current_framebuffer_texture_->size() !=
        offscreen_stencil_renderbuffer_size_) {
      gl_->BindRenderbuffer(GL_RENDERBUFFER,
                            offscreen_stencil_renderbuffer_id_);
      gl_->RenderbufferStorage(GL_RENDERBUFFER, GL_STENCIL_INDEX8,
                               current_framebuffer_texture_->size().width(),
                               current_framebuffer_texture_->size().height());
      gl_->BindRenderbuffer(GL_RENDERBUFFER, 0);
      offscreen_stencil_renderbuffer_size_ =
          current_framebuffer_texture_->size();
    }
    gl_->FramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT,
                                 GL_RENDERBUFFER,
                                 offscreen_stencil_renderbuffer_id_);
  }

  DCHECK(gl_->CheckFramebufferStatus(GL_FRAMEBUFFER) ==
             GL_FRAMEBUFFER_COMPLETE ||
         IsContextLost());

  if (overdraw_feedback_) {
    SetupOverdrawFeedback();
    SetStencilEnabled(true);
  } else {
    SetStencilEnabled(false);
  }
}

void GLRenderer::SetScissorTestRect(const gfx::Rect& scissor_rect) {
  EnsureScissorTestEnabled();

  // Don't unnecessarily ask the context to change the scissor, because it
  // may cause undesired GPU pipeline flushes.
  if (scissor_rect == scissor_rect_)
    return;

  scissor_rect_ = scissor_rect;
  FlushTextureQuadCache(SHARED_BINDING);
  gl_->Scissor(scissor_rect.x(), scissor_rect.y(), scissor_rect.width(),
               scissor_rect.height());
}

void GLRenderer::SetViewport() {
  gl_->Viewport(current_window_space_viewport_.x(),
                current_window_space_viewport_.y(),
                current_window_space_viewport_.width(),
                current_window_space_viewport_.height());
}

void GLRenderer::InitializeSharedObjects() {
  TRACE_EVENT0("viz", "GLRenderer::InitializeSharedObjects");

  // Create an FBO for doing offscreen rendering.
  gl_->GenFramebuffers(1, &offscreen_framebuffer_id_);

  shared_geometry_ =
      std::make_unique<StaticGeometryBinding>(gl_, QuadVertexRect());
  clipped_geometry_ = std::make_unique<DynamicGeometryBinding>(gl_);
}

void GLRenderer::PrepareGeometry(BoundGeometry binding) {
  if (binding == bound_geometry_) {
    return;
  }

  switch (binding) {
    case SHARED_BINDING:
      shared_geometry_->PrepareForDraw();
      break;
    case CLIPPED_BINDING:
      clipped_geometry_->PrepareForDraw();
      break;
    case NO_BINDING:
      break;
  }
  bound_geometry_ = binding;
}

void GLRenderer::SetUseProgram(const ProgramKey& program_key_no_color,
                               const gfx::ColorSpace& src_color_space,
                               const gfx::ColorSpace& dst_color_space) {
  DCHECK(dst_color_space.IsValid());

  ProgramKey program_key = program_key_no_color;
  const gfx::ColorTransform* color_transform =
      GetColorTransform(src_color_space, dst_color_space);
  program_key.SetColorTransform(color_transform);

  const bool is_root_render_pass =
      current_frame()->current_render_pass == current_frame()->root_render_pass;
  const SkMatrix44& output_color_matrix = output_surface_->color_matrix();
  const bool has_output_color_matrix =
      is_root_render_pass && !output_color_matrix.isIdentity();

  program_key.set_has_output_color_matrix(has_output_color_matrix);

  // Create and set the program if needed.
  std::unique_ptr<Program>& program = program_cache_[program_key];
  if (!program) {
    program.reset(new Program);
    program->Initialize(output_surface_->context_provider(), program_key);
  }
  DCHECK(program);
  if (current_program_ != program.get()) {
    current_program_ = program.get();
    gl_->UseProgram(current_program_->program());
  }
  if (!current_program_->initialized()) {
    DCHECK(IsContextLost());
    return;
  }

  // Set uniforms that are common to all programs.
  if (current_program_->sampler_location() != -1)
    gl_->Uniform1i(current_program_->sampler_location(), 0);
  if (current_program_->viewport_location() != -1) {
    float viewport[4] = {
        static_cast<float>(current_window_space_viewport_.x()),
        static_cast<float>(current_window_space_viewport_.y()),
        static_cast<float>(current_window_space_viewport_.width()),
        static_cast<float>(current_window_space_viewport_.height()),
    };
    gl_->Uniform4fv(current_program_->viewport_location(), 1, viewport);
  }
  if (current_program_->lut_texture_location() != -1) {
    ColorLUTCache::LUT lut = color_lut_cache_.GetLUT(color_transform);
    gl_->ActiveTexture(GL_TEXTURE5);
    gl_->BindTexture(GL_TEXTURE_2D, lut.texture);
    gl_->Uniform1i(current_program_->lut_texture_location(), 5);
    gl_->Uniform1f(current_program_->lut_size_location(), lut.size);
    gl_->ActiveTexture(GL_TEXTURE0);
  }

  if (has_output_color_matrix) {
    DCHECK_NE(current_program_->output_color_matrix_location(), -1);
    float matrix[16];
    output_color_matrix.asColMajorf(matrix);
    gl_->UniformMatrix4fv(current_program_->output_color_matrix_location(), 1,
                          false, matrix);
  }
}

const Program* GLRenderer::GetProgramIfInitialized(
    const ProgramKey& desc) const {
  const auto found = program_cache_.find(desc);
  if (found == program_cache_.end())
    return nullptr;
  return found->second.get();
}

const gfx::ColorTransform* GLRenderer::GetColorTransform(
    const gfx::ColorSpace& src,
    const gfx::ColorSpace& dst) {
  std::unique_ptr<gfx::ColorTransform>& transform =
      color_transform_cache_[dst][src];
  if (!transform) {
    transform = gfx::ColorTransform::NewColorTransform(
        src, dst, gfx::ColorTransform::Intent::INTENT_PERCEPTUAL);
  }
  return transform.get();
}

void GLRenderer::CleanupSharedObjects() {
  shared_geometry_ = nullptr;

  gl_->ReleaseShaderCompiler();
  for (auto& iter : program_cache_)
    iter.second->Cleanup(gl_);
  program_cache_.clear();
  color_transform_cache_.clear();

  if (offscreen_framebuffer_id_)
    gl_->DeleteFramebuffers(1, &offscreen_framebuffer_id_);

  if (offscreen_stencil_renderbuffer_id_)
    gl_->DeleteRenderbuffers(1, &offscreen_stencil_renderbuffer_id_);
}

void GLRenderer::ReinitializeGLState() {
  is_scissor_enabled_ = false;
  scissor_rect_ = gfx::Rect();
  stencil_shadow_ = false;
  blend_shadow_ = true;
  current_program_ = nullptr;

  RestoreGLState();
}

void GLRenderer::RestoreGLState() {
  // This restores the current GLRenderer state to the GL context.
  bound_geometry_ = NO_BINDING;
  PrepareGeometry(SHARED_BINDING);

  gl_->Disable(GL_DEPTH_TEST);
  gl_->Disable(GL_CULL_FACE);
  gl_->ColorMask(true, true, true, true);
  gl_->BlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
  gl_->ActiveTexture(GL_TEXTURE0);

  if (current_program_)
    gl_->UseProgram(current_program_->program());

  if (stencil_shadow_)
    gl_->Enable(GL_STENCIL_TEST);
  else
    gl_->Disable(GL_STENCIL_TEST);

  if (blend_shadow_)
    gl_->Enable(GL_BLEND);
  else
    gl_->Disable(GL_BLEND);

  if (is_scissor_enabled_)
    gl_->Enable(GL_SCISSOR_TEST);
  else
    gl_->Disable(GL_SCISSOR_TEST);

  gl_->Scissor(scissor_rect_.x(), scissor_rect_.y(), scissor_rect_.width(),
               scissor_rect_.height());
}

bool GLRenderer::IsContextLost() {
  return gl_->GetGraphicsResetStatusKHR() != GL_NO_ERROR;
}

void GLRenderer::ScheduleCALayers() {
  // The use of OverlayTextures for RenderPasses is only supported on the code
  // paths for |release_overlay_resources_after_gpu_query| at the moment. See
  // SwapBuffersComplete for notes on the missing support for other paths. This
  // method uses ScheduleRenderPassDrawQuad to send RenderPass outputs as
  // overlays, so it can only be used because this setting is true.
  if (!settings_->release_overlay_resources_after_gpu_query)
    return;

  scoped_refptr<CALayerOverlaySharedState> shared_state;
  size_t copied_render_pass_count = 0;

  for (const CALayerOverlay& ca_layer_overlay :
       current_frame()->ca_layer_overlay_list) {
    if (ca_layer_overlay.rpdq) {
      std::unique_ptr<OverlayTexture> overlay_texture =
          ScheduleRenderPassDrawQuad(&ca_layer_overlay);
      if (overlay_texture)
        awaiting_swap_overlay_textures_.push_back(std::move(overlay_texture));
      shared_state = nullptr;
      ++copied_render_pass_count;
      continue;
    }

    ResourceId contents_resource_id = ca_layer_overlay.contents_resource_id;
    unsigned texture_id = 0;
    if (contents_resource_id) {
      pending_overlay_resources_.push_back(
          std::make_unique<DisplayResourceProvider::ScopedReadLockGL>(
              resource_provider_, contents_resource_id));
      texture_id = pending_overlay_resources_.back()->texture_id();
    }
    GLfloat contents_rect[4] = {
        ca_layer_overlay.contents_rect.x(), ca_layer_overlay.contents_rect.y(),
        ca_layer_overlay.contents_rect.width(),
        ca_layer_overlay.contents_rect.height(),
    };
    GLfloat bounds_rect[4] = {
        ca_layer_overlay.bounds_rect.x(), ca_layer_overlay.bounds_rect.y(),
        ca_layer_overlay.bounds_rect.width(),
        ca_layer_overlay.bounds_rect.height(),
    };
    GLboolean is_clipped = ca_layer_overlay.shared_state->is_clipped;
    GLfloat clip_rect[4] = {ca_layer_overlay.shared_state->clip_rect.x(),
                            ca_layer_overlay.shared_state->clip_rect.y(),
                            ca_layer_overlay.shared_state->clip_rect.width(),
                            ca_layer_overlay.shared_state->clip_rect.height()};
    GLint sorting_context_id =
        ca_layer_overlay.shared_state->sorting_context_id;
    GLfloat transform[16];
    ca_layer_overlay.shared_state->transform.asColMajorf(transform);
    unsigned filter = ca_layer_overlay.filter;

    if (ca_layer_overlay.shared_state != shared_state) {
      shared_state = ca_layer_overlay.shared_state;
      gl_->ScheduleCALayerSharedStateCHROMIUM(
          ca_layer_overlay.shared_state->opacity, is_clipped, clip_rect,
          sorting_context_id, transform);
    }
    gl_->ScheduleCALayerCHROMIUM(
        texture_id, contents_rect, ca_layer_overlay.background_color,
        ca_layer_overlay.edge_aa_mask, bounds_rect, filter);
  }

  ReduceAvailableOverlayTextures(awaiting_swap_overlay_textures_);
}

void GLRenderer::ScheduleDCLayers() {
  scoped_refptr<DCLayerOverlaySharedState> shared_state;
  for (DCLayerOverlay& dc_layer_overlay :
       current_frame()->dc_layer_overlay_list) {
    DCHECK(!dc_layer_overlay.rpdq);

    int i = 0;
    unsigned texture_ids[DrawQuad::Resources::kMaxResourceIdCount] = {};
    int ids_to_send = 0;

    for (const auto& contents_resource_id : dc_layer_overlay.resources) {
      if (contents_resource_id) {
        pending_overlay_resources_.push_back(
            std::make_unique<DisplayResourceProvider::ScopedReadLockGL>(
                resource_provider_, contents_resource_id));
        texture_ids[i] = pending_overlay_resources_.back()->texture_id();
        ids_to_send = i + 1;
      }
      i++;
    }
    GLfloat contents_rect[4] = {
        dc_layer_overlay.contents_rect.x(), dc_layer_overlay.contents_rect.y(),
        dc_layer_overlay.contents_rect.width(),
        dc_layer_overlay.contents_rect.height(),
    };
    GLfloat bounds_rect[4] = {
        dc_layer_overlay.bounds_rect.x(), dc_layer_overlay.bounds_rect.y(),
        dc_layer_overlay.bounds_rect.width(),
        dc_layer_overlay.bounds_rect.height(),
    };
    GLboolean is_clipped = dc_layer_overlay.shared_state->is_clipped;
    GLfloat clip_rect[4] = {dc_layer_overlay.shared_state->clip_rect.x(),
                            dc_layer_overlay.shared_state->clip_rect.y(),
                            dc_layer_overlay.shared_state->clip_rect.width(),
                            dc_layer_overlay.shared_state->clip_rect.height()};
    GLint z_order = dc_layer_overlay.shared_state->z_order;
    GLfloat transform[16];
    dc_layer_overlay.shared_state->transform.asColMajorf(transform);
    unsigned filter = dc_layer_overlay.filter;

    if (dc_layer_overlay.shared_state != shared_state) {
      shared_state = dc_layer_overlay.shared_state;
      gl_->ScheduleDCLayerSharedStateCHROMIUM(
          dc_layer_overlay.shared_state->opacity, is_clipped, clip_rect,
          z_order, transform);
    }
    if (ids_to_send > 0) {
      gl_->SetColorSpaceMetadataCHROMIUM(
          texture_ids[0],
          reinterpret_cast<GLColorSpace>(&dc_layer_overlay.color_space));
    }
    gl_->ScheduleDCLayerCHROMIUM(ids_to_send, texture_ids, contents_rect,
                                 dc_layer_overlay.background_color,
                                 dc_layer_overlay.edge_aa_mask, bounds_rect,
                                 filter, dc_layer_overlay.is_protected_video);
  }
}

void GLRenderer::ScheduleOverlays() {
  if (current_frame()->overlay_list.empty())
    return;

  OverlayCandidateList& overlays = current_frame()->overlay_list;
  for (const auto& overlay_candidate : overlays) {
    unsigned texture_id = 0;
    if (overlay_candidate.use_output_surface_for_resource) {
      texture_id = output_surface_->GetOverlayTextureId();
      DCHECK(texture_id || IsContextLost());
    } else {
      pending_overlay_resources_.push_back(
          std::make_unique<DisplayResourceProvider::ScopedReadLockGL>(
              resource_provider_, overlay_candidate.resource_id));
      texture_id = pending_overlay_resources_.back()->texture_id();
    }

    context_support_->ScheduleOverlayPlane(
        overlay_candidate.plane_z_order, overlay_candidate.transform,
        texture_id, ToNearestRect(overlay_candidate.display_rect),
        overlay_candidate.uv_rect, !overlay_candidate.is_opaque,
        overlay_candidate.gpu_fence_id);
  }
}

// This function draws the RenderPassDrawQuad into a temporary
// texture/framebuffer, and then copies the result into an IOSurface. The
// inefficient (but simple) way to do this would be to:
//   1. Allocate a framebuffer the size of the screen.
//   2. Draw using all the normal RPDQ draw logic.
//
// Instead, this method does the following:
//   1. Configure parameters as if drawing to a framebuffer the size of the
//   screen. This reuses most of the RPDQ draw logic.
//   2. Update parameters to draw into a framebuffer only as large as needed.
//   3. Fix shader uniforms that were broken by (2).
//
// Then:
//   4. Allocate an IOSurface as the drawing destination.
//   5. Draw the RPDQ.
void GLRenderer::CopyRenderPassDrawQuadToOverlayResource(
    const CALayerOverlay* ca_layer_overlay,
    std::unique_ptr<OverlayTexture>* overlay_texture,
    gfx::RectF* new_bounds) {
  // Don't carry over any GL state from previous RenderPass draw operations.
  ReinitializeGLState();
  auto contents_texture_it =
      render_pass_textures_.find(ca_layer_overlay->rpdq->render_pass_id);
  DCHECK(contents_texture_it != render_pass_textures_.end());

  // Configure parameters as if drawing to a framebuffer the size of the
  // screen.
  DrawRenderPassDrawQuadParams params;
  params.quad = ca_layer_overlay->rpdq;
  params.flip_texture = true;
  params.contents_texture = &contents_texture_it->second;
  params.quad_to_target_transform =
      params.quad->shared_quad_state->quad_to_target_transform;
  params.tex_coord_rect = params.quad->tex_coord_rect;

  // Calculate projection and window matrices using InitializeViewport(). This
  // requires creating a dummy DrawingFrame.
  {
    DrawingFrame dummy_frame;
    gfx::Rect frame_rect(current_frame()->device_viewport_size);
    force_drawing_frame_framebuffer_unflipped_ = true;
    InitializeViewport(&dummy_frame, frame_rect, frame_rect, frame_rect.size());
    force_drawing_frame_framebuffer_unflipped_ = false;
    params.projection_matrix = dummy_frame.projection_matrix;
    params.window_matrix = dummy_frame.window_matrix;
  }

  // Perform basic initialization with the screen-sized viewport.
  if (!InitializeRPDQParameters(&params))
    return;

  if (!UpdateRPDQWithSkiaFilters(&params))
    return;

  // |params.dst_rect| now contain values that reflect a potentially increased
  // size quad.
  gfx::RectF updated_dst_rect = params.dst_rect;
  gfx::Size dst_pixel_size = gfx::ToCeiledSize(updated_dst_rect.size());

  int iosurface_width = dst_pixel_size.width();
  int iosurface_height = dst_pixel_size.height();
  if (!settings_->dont_round_texture_sizes_for_pixel_tests) {
    // Round the size of the IOSurface to a multiple of 64 pixels. This reduces
    // memory fragmentation. https://crbug.com/146070. This also allows
    // IOSurfaces to be more easily reused during a resize operation.
    int iosurface_multiple = 64;
    iosurface_width =
        cc::MathUtil::CheckedRoundUp(iosurface_width, iosurface_multiple);
    iosurface_height =
        cc::MathUtil::CheckedRoundUp(iosurface_height, iosurface_multiple);
  }

  *overlay_texture = FindOrCreateOverlayTexture(
      params.quad->render_pass_id, iosurface_width, iosurface_height,
      current_frame()->root_render_pass->color_space);
  *new_bounds = gfx::RectF(updated_dst_rect.origin(),
                           gfx::SizeF((*overlay_texture)->texture.size()));

  // Calculate new projection and window matrices for a minimally sized viewport
  // using InitializeViewport(). This requires creating a dummy DrawingFrame.
  {
    DrawingFrame dummy_frame;
    force_drawing_frame_framebuffer_unflipped_ = true;
    gfx::Rect frame_rect =
        gfx::Rect(0, 0, updated_dst_rect.width(), updated_dst_rect.height());
    InitializeViewport(&dummy_frame, frame_rect, frame_rect, frame_rect.size());
    force_drawing_frame_framebuffer_unflipped_ = false;
    params.projection_matrix = dummy_frame.projection_matrix;
    params.window_matrix = dummy_frame.window_matrix;
  }

  // Calculate a new quad_to_target_transform.
  params.quad_to_target_transform = gfx::Transform();
  params.quad_to_target_transform.Translate(-updated_dst_rect.x(),
                                            -updated_dst_rect.y());

  // Antialiasing works by fading out content that is close to the edge of the
  // viewport. All of these values need to be recalculated.
  if (params.use_aa) {
    current_window_space_viewport_ =
        gfx::Rect(0, 0, updated_dst_rect.width(), updated_dst_rect.height());
    gfx::Transform quad_rect_matrix;
    QuadRectTransform(&quad_rect_matrix, params.quad_to_target_transform,
                      updated_dst_rect);
    params.contents_device_transform =
        params.window_matrix * params.projection_matrix * quad_rect_matrix;
    bool clipped = false;
    params.contents_device_transform.FlattenTo2d();
    gfx::QuadF device_layer_quad = cc::MathUtil::MapQuad(
        params.contents_device_transform, SharedGeometryQuad(), &clipped);
    LayerQuad device_layer_edges(device_layer_quad);
    InflateAntiAliasingDistances(device_layer_quad, &device_layer_edges,
                                 params.edge);
  }

  // Establish destination texture.
  GLuint temp_fbo;
  gl_->GenFramebuffers(1, &temp_fbo);
  gl_->BindFramebuffer(GL_FRAMEBUFFER, temp_fbo);
  gl_->FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                            (*overlay_texture)->texture.target(),
                            (*overlay_texture)->texture.id(), 0);
  DCHECK(gl_->CheckFramebufferStatus(GL_FRAMEBUFFER) ==
             GL_FRAMEBUFFER_COMPLETE ||
         IsContextLost());

  // Clear to 0 to ensure the background is transparent.
  gl_->ClearColor(0, 0, 0, 0);
  gl_->Clear(GL_COLOR_BUFFER_BIT);

  UpdateRPDQTexturesForSampling(&params);
  UpdateRPDQBlendMode(&params);
  ChooseRPDQProgram(&params, (*overlay_texture)->texture.color_space());
  UpdateRPDQUniforms(&params);

  // Prior to drawing, set up the destination framebuffer and viewport.
  gl_->BindFramebuffer(GL_FRAMEBUFFER, temp_fbo);
  gl_->Viewport(0, 0, updated_dst_rect.width(), updated_dst_rect.height());

  DrawRPDQ(params);
  if (params.background_texture) {
    gl_->DeleteTextures(1, &params.background_texture);
    params.background_texture = 0;
  }
  gl_->DeleteFramebuffers(1, &temp_fbo);
}

std::unique_ptr<GLRenderer::OverlayTexture>
GLRenderer::FindOrCreateOverlayTexture(const RenderPassId& render_pass_id,
                                       int width,
                                       int height,
                                       const gfx::ColorSpace& color_space) {
  // First try to use a texture for the same RenderPassId, to keep things more
  // stable and less likely to clobber each others textures.
  auto match_with_id = [&](const std::unique_ptr<OverlayTexture>& overlay) {
    return overlay->render_pass_id == render_pass_id &&
           overlay->texture.size().width() >= width &&
           overlay->texture.size().height() >= height &&
           overlay->texture.size().width() <= width * 2 &&
           overlay->texture.size().height() <= height * 2;
  };
  auto it = std::find_if(available_overlay_textures_.begin(),
                         available_overlay_textures_.end(), match_with_id);
  if (it != available_overlay_textures_.end()) {
    std::unique_ptr<OverlayTexture> result = std::move(*it);
    available_overlay_textures_.erase(it);

    result->render_pass_id = render_pass_id;
    return result;
  }

  // Then fallback to trying other textures that still match.
  auto match = [&](const std::unique_ptr<OverlayTexture>& overlay) {
    return overlay->texture.size().width() >= width &&
           overlay->texture.size().height() >= height &&
           overlay->texture.size().width() <= width * 2 &&
           overlay->texture.size().height() <= height * 2;
  };
  it = std::find_if(available_overlay_textures_.begin(),
                    available_overlay_textures_.end(), match);
  if (it != available_overlay_textures_.end()) {
    std::unique_ptr<OverlayTexture> result = std::move(*it);
    available_overlay_textures_.erase(it);

    result->render_pass_id = render_pass_id;
    return result;
  }

  // Make a new texture if we could not find a match. Sadtimes.
  auto result = std::make_unique<OverlayTexture>();
  result->texture = ScopedGpuMemoryBufferTexture(
      output_surface_->context_provider(),
      gfx::Size(width, height), color_space);
  result->render_pass_id = render_pass_id;
  return result;
}

void GLRenderer::ReduceAvailableOverlayTextures(
    const std::vector<std::unique_ptr<OverlayTexture>>& most_recent) {
  // Overlay resources may get returned back to the compositor at varying rates,
  // so we may get a number of resources returned at once, then none for a
  // while. As such, we want to hold onto enough resources to not have to create
  // any when none are released for a while. Emperical study by erikchen@ on
  // crbug.com/636884 found that saving 5 spare textures per RenderPass was
  // sufficient for important benchmarks. This seems to imply that the OS may
  // hold up to 5 frames of textures before releasing them.
  static const int kKeepCountPerRenderPass = 5;

  // In order to accomodate the above requirements, we hold any released texture
  // in the |available_overlay_textures_| set for up to 5 frames before
  // discarding it.
  for (const auto& overlay : available_overlay_textures_)
    overlay->frames_waiting_for_reuse++;
  base::EraseIf(available_overlay_textures_,
                [](const std::unique_ptr<OverlayTexture>& overlay) {
                  return overlay->frames_waiting_for_reuse >=
                         kKeepCountPerRenderPass;
                });
}

std::unique_ptr<GLRenderer::OverlayTexture>
GLRenderer::ScheduleRenderPassDrawQuad(const CALayerOverlay* ca_layer_overlay) {
  DCHECK(ca_layer_overlay->rpdq);

  std::unique_ptr<OverlayTexture> overlay_texture;
  gfx::RectF new_bounds;
  CopyRenderPassDrawQuadToOverlayResource(ca_layer_overlay, &overlay_texture,
                                          &new_bounds);
  if (!overlay_texture)
    return {};

  GLfloat contents_rect[4] = {
      ca_layer_overlay->contents_rect.x(), ca_layer_overlay->contents_rect.y(),
      ca_layer_overlay->contents_rect.width(),
      ca_layer_overlay->contents_rect.height(),
  };
  GLfloat bounds_rect[4] = {
      new_bounds.x(), new_bounds.y(), new_bounds.width(), new_bounds.height(),
  };
  GLboolean is_clipped = ca_layer_overlay->shared_state->is_clipped;
  GLfloat clip_rect[4] = {ca_layer_overlay->shared_state->clip_rect.x(),
                          ca_layer_overlay->shared_state->clip_rect.y(),
                          ca_layer_overlay->shared_state->clip_rect.width(),
                          ca_layer_overlay->shared_state->clip_rect.height()};
  GLint sorting_context_id = ca_layer_overlay->shared_state->sorting_context_id;
  SkMatrix44 transform = ca_layer_overlay->shared_state->transform;
  GLfloat gl_transform[16];
  transform.asColMajorf(gl_transform);
  unsigned filter = ca_layer_overlay->filter;

  // The alpha has already been applied when copying the RPDQ to an IOSurface.
  GLfloat alpha = 1;
  gl_->ScheduleCALayerSharedStateCHROMIUM(alpha, is_clipped, clip_rect,
                                          sorting_context_id, gl_transform);
  gl_->ScheduleCALayerCHROMIUM(overlay_texture->texture.id(), contents_rect,
                               ca_layer_overlay->background_color,
                               ca_layer_overlay->edge_aa_mask, bounds_rect,
                               filter);
  return overlay_texture;
}

void GLRenderer::SetupOverdrawFeedback() {
  gl_->StencilFunc(GL_ALWAYS, 1, 0xffffffff);
  // First two values are ignored as test always passes.
  gl_->StencilOp(GL_KEEP, GL_KEEP, GL_INCR);
  gl_->StencilMask(0xffffffff);
}

void GLRenderer::FlushOverdrawFeedback(const gfx::Rect& output_rect) {
  DCHECK(stencil_shadow_);

  // Test only, keep everything.
  gl_->StencilOp(GL_KEEP, GL_KEEP, GL_KEEP);

  EnsureScissorTestDisabled();
  SetBlendEnabled(true);

  PrepareGeometry(SHARED_BINDING);

  SetUseProgram(ProgramKey::DebugBorder(), gfx::ColorSpace::CreateSRGB(),
                current_frame()->root_render_pass->color_space);

  gfx::Transform render_matrix;
  render_matrix.Translate(0.5 * output_rect.width() + output_rect.x(),
                          0.5 * output_rect.height() + output_rect.y());
  render_matrix.Scale(output_rect.width(), output_rect.height());
  SetShaderMatrix(current_frame()->projection_matrix * render_matrix);

  // Produce hinting for the amount of overdraw on screen for each pixel by
  // drawing hint colors to the framebuffer based on the current stencil value.
  struct {
    int multiplier;
    GLenum func;
    GLint ref;
    SkColor color;
  } stencil_tests[] = {
      {1, GL_EQUAL, 2, 0x2f0000ff},  // Blue: Overdrawn once.
      {2, GL_EQUAL, 3, 0x2f00ff00},  // Green: Overdrawn twice.
      {3, GL_EQUAL, 4, 0x3fff0000},  // Pink: Overdrawn three times.
      {4, GL_LESS, 4, 0x7fff0000},   // Red: Overdrawn four or more times.
  };

  // Occlusion queries can be expensive, so only collect trace data if we select
  // cc.debug.overdraw.
  bool tracing_enabled;
  TRACE_EVENT_CATEGORY_GROUP_ENABLED(TRACE_DISABLED_BY_DEFAULT("viz.overdraw"),
                                     &tracing_enabled);

  // Trace only the root render pass.
  if (current_frame()->current_render_pass != current_frame()->root_render_pass)
    tracing_enabled = false;

  // ARB_occlusion_query is required for tracing.
  if (!use_occlusion_query_)
    tracing_enabled = false;

  // Use the current surface area as max result. The effect is that overdraw
  // is reported as a percentage of the output surface size. ie. 2x overdraw
  // for the whole screen is reported as 200.
  int max_result = current_surface_size_.GetArea();
  DCHECK_GT(max_result, 0);

  OverdrawFeedbackCallback overdraw_feedback_callback = base::Bind(
      &GLRenderer::ProcessOverdrawFeedback, weak_ptr_factory_.GetWeakPtr(),
      base::Owned(new std::vector<int>), arraysize(stencil_tests), max_result);

  for (const auto& test : stencil_tests) {
    GLuint query = 0;
    if (tracing_enabled) {
      gl_->GenQueriesEXT(1, &query);
      gl_->BeginQueryEXT(GL_SAMPLES_PASSED_ARB, query);
    }

    gl_->StencilFunc(test.func, test.ref, 0xffffffff);
    // Transparent color unless color-coding of overdraw is enabled.
    SetShaderColor(settings_->show_overdraw_feedback ? test.color : 0, 1.f);
    gl_->DrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, nullptr);

    if (query) {
      gl_->EndQueryEXT(GL_SAMPLES_PASSED_ARB);
      context_support_->SignalQuery(
          query,
          base::Bind(overdraw_feedback_callback, query, test.multiplier));
    }
  }
}

void GLRenderer::ProcessOverdrawFeedback(std::vector<int>* overdraw,
                                         size_t num_expected_results,
                                         int max_result,
                                         unsigned query,
                                         int multiplier) {
  unsigned result = 0;
  if (query) {
    gl_->GetQueryObjectuivEXT(query, GL_QUERY_RESULT_EXT, &result);
    gl_->DeleteQueriesEXT(1, &query);
  }

  // Apply multiplier to get the amount of overdraw.
  overdraw->push_back(result * multiplier);

  // Return early if we are expecting more results.
  if (overdraw->size() < num_expected_results)
    return;

  // Report GPU overdraw as a percentage of |max_result|.
  TRACE_COUNTER1(
      TRACE_DISABLED_BY_DEFAULT("viz.overdraw"), "GPU Overdraw",
      (std::accumulate(overdraw->begin(), overdraw->end(), 0) * 100) /
          max_result);
}

void GLRenderer::UpdateRenderPassTextures(
    const RenderPassList& render_passes_in_draw_order,
    const base::flat_map<RenderPassId, RenderPassRequirements>&
        render_passes_in_frame) {
  // Collect RenderPass textures that should be deleted.
  std::vector<RenderPassId> passes_to_delete;
  for (const auto& pair : render_pass_textures_) {
    auto render_pass_it = render_passes_in_frame.find(pair.first);
    if (render_pass_it == render_passes_in_frame.end()) {
      passes_to_delete.push_back(pair.first);
      continue;
    }
    const RenderPassRequirements& requirements = render_pass_it->second;
    const ScopedRenderPassTexture& texture = pair.second;
    bool size_appropriate =
        texture.size().width() >= requirements.size.width() &&
        texture.size().height() >= requirements.size.height();
    bool mipmap_appropriate = !requirements.mipmap || texture.mipmap();
    if (!size_appropriate || !mipmap_appropriate)
      passes_to_delete.push_back(pair.first);
  }
  // Delete RenderPass textures from the previous frame that will not be used
  // again.
  for (size_t i = 0; i < passes_to_delete.size(); ++i)
    render_pass_textures_.erase(passes_to_delete[i]);
}

ResourceFormat GLRenderer::BackbufferFormat() const {
  const auto& caps = output_surface_->context_provider()->ContextCapabilities();
  if (current_frame()->current_render_pass->color_space.IsHDR()) {
    // If a platform does not support half-float renderbuffers then it should
    // not should request HDR rendering.
    DCHECK(caps.texture_half_float_linear);
    DCHECK(caps.color_buffer_half_float_rgba);
    return RGBA_F16;
  }
  return PlatformColor::BestSupportedTextureFormat(caps);
}

void GLRenderer::AllocateRenderPassResourceIfNeeded(
    const RenderPassId& render_pass_id,
    const RenderPassRequirements& requirements) {
  auto contents_texture_it = render_pass_textures_.find(render_pass_id);
  if (contents_texture_it != render_pass_textures_.end())
    return;

  ScopedRenderPassTexture contents_texture(
      output_surface_->context_provider(), requirements.size,
      BackbufferFormat(), current_frame()->current_render_pass->color_space,
      requirements.mipmap);
  render_pass_textures_[render_pass_id] = std::move(contents_texture);
}

bool GLRenderer::IsRenderPassResourceAllocated(
    const RenderPassId& render_pass_id) const {
  auto texture_it = render_pass_textures_.find(render_pass_id);
  return texture_it != render_pass_textures_.end();
}

gfx::Size GLRenderer::GetRenderPassBackingPixelSize(
    const RenderPassId& render_pass_id) {
  auto texture_it = render_pass_textures_.find(render_pass_id);
  DCHECK(texture_it != render_pass_textures_.end());
  return texture_it->second.size();
}

}  // namespace viz