[wip/exp] cc: Measure the amount of overdraw.

cc/output/gl_renderer.h

Index: cc/output/gl_renderer.h
diff --git a/cc/output/gl_renderer.h b/cc/output/gl_renderer.h
index e00b475fcd76ca1e685c34572ab8159eb03d28ef..0a456913c74fca76002c72789d21b3a98758fdb0 100644
--- a/cc/output/gl_renderer.h
+++ b/cc/output/gl_renderer.h
@@ -180,31 +180,31 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
 
   const TileDrawQuad* CanPassBeDrawnDirectly(const RenderPass* pass) override;
 
-  void DrawRenderPassQuad(const RenderPassDrawQuad* quadi,
+  bool DrawRenderPassQuad(const RenderPassDrawQuad* quadi,
                           const gfx::QuadF* clip_region);
-  void DrawRenderPassQuadInternal(DrawRenderPassDrawQuadParams* params);
-  void DrawSolidColorQuad(const SolidColorDrawQuad* quad,
+  bool DrawRenderPassQuadInternal(DrawRenderPassDrawQuadParams* params);
+  bool DrawSolidColorQuad(const SolidColorDrawQuad* quad,
                           const gfx::QuadF* clip_region);
-  void DrawStreamVideoQuad(const StreamVideoDrawQuad* quad,
+  bool DrawStreamVideoQuad(const StreamVideoDrawQuad* quad,
                            const gfx::QuadF* clip_region);
   void DrawTextureQuad(const TextureDrawQuad* quad,
                        const gfx::QuadF* clip_region);
-  void EnqueueTextureQuad(const TextureDrawQuad* quad,
+  bool EnqueueTextureQuad(const TextureDrawQuad* quad,
                           const gfx::QuadF* clip_region);
   void FlushTextureQuadCache(BoundGeometry flush_binding);
-  void DrawTileQuad(const TileDrawQuad* quad, const gfx::QuadF* clip_region);
-  void DrawContentQuad(const ContentDrawQuadBase* quad,
+  bool DrawTileQuad(const TileDrawQuad* quad, const gfx::QuadF* clip_region);
+  bool DrawContentQuad(const ContentDrawQuadBase* quad,
                        ResourceId resource_id,
                        const gfx::QuadF* clip_region);
-  void DrawContentQuadAA(const ContentDrawQuadBase* quad,
+  bool DrawContentQuadAA(const ContentDrawQuadBase* quad,
                          ResourceId resource_id,
                          const gfx::Transform& device_transform,
                          const gfx::QuadF& aa_quad,
                          const gfx::QuadF* clip_region);
-  void DrawContentQuadNoAA(const ContentDrawQuadBase* quad,
+  bool DrawContentQuadNoAA(const ContentDrawQuadBase* quad,
                            ResourceId resource_id,
                            const gfx::QuadF* clip_region);
-  void DrawYUVVideoQuad(const YUVVideoDrawQuad* quad,
+  bool DrawYUVVideoQuad(const YUVVideoDrawQuad* quad,
                         const gfx::QuadF* clip_region);
 
   void SetShaderOpacity(const DrawQuad* quad);
@@ -364,6 +364,8 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
   unsigned offscreen_stencil_renderbuffer_id_ = 0;
   gfx::Size offscreen_stencil_renderbuffer_size_;
 
+  size_t area_drawn_ = 0;
+
   base::WeakPtrFactory<GLRenderer> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GLRenderer);