Add logic to GLRenderer to support RenderPassDrawQuad copying.

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 30c227367f04c417ca458243429848b411ac9214..51161a14b025254c9c98681bf7a62c08f4c8c64d 100644
--- a/cc/output/gl_renderer.h
+++ b/cc/output/gl_renderer.h
@@ -20,6 +20,7 @@
 #include "cc/quads/solid_color_draw_quad.h"
 #include "cc/quads/tile_draw_quad.h"
 #include "cc/quads/yuv_video_draw_quad.h"
+#include "cc/resources/scoped_resource.h"
 #include "ui/gfx/geometry/quad_f.h"
 
 class SkBitmap;
@@ -148,6 +149,11 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
  private:
   friend class GLRendererShaderPixelTest;
   friend class GLRendererShaderTest;
+  FRIEND_TEST_ALL_PREFIXES(GLRendererRenderPassDrawQuadCopierTest, Reuse);
+  FRIEND_TEST_ALL_PREFIXES(GLRendererRenderPassDrawQuadCopierTest,
+                           ReleaseResources);
+  FRIEND_TEST_ALL_PREFIXES(GLRendererRenderPassDrawQuadCopierTest,
+                           MaxCacheSize);
 
   static void ToGLMatrix(float* gl_matrix, const gfx::Transform& transform);
 
@@ -263,6 +269,16 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
   void ScheduleCALayers(DrawingFrame* frame);
   void ScheduleOverlays(DrawingFrame* frame);
 
+  void OverlayResourceNoLongerInUse(GLuint texture);
+  ResourceId CreateOrReuseIOSurface(const gfx::Size& size);
+  void DeleteIOSurfacesOverCacheLimit();
+
+  // RenderPassDrawQuadCopier
+  bool CopyRenderPassDrawQuadToIOSurface(const RenderPassDrawQuad* quad,
+                                         ResourceId* resource_id) override;
+  void ReleaseIOSurfaces(const std::vector<ResourceId>& resources) override;
+  void UpdateCopyCountForFrame(size_t count) override;
+
   using OverlayResourceLock =
       std::unique_ptr<ResourceProvider::ScopedReadLockGL>;
   using OverlayResourceLockList = std::vector<OverlayResourceLock>;
@@ -521,6 +537,11 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
   bool use_blend_equation_advanced_;
   bool use_blend_equation_advanced_coherent_;
 
+  // Keep an LRU buffer of GMB resources to encourage reuse.

[ccameron, 2016/07/20 05:32:19]

Can we use/augment the existing
cc::ResourcePool::CreateForGpuMemoryBufferResources instead?

[Also, I'd be a fan of doing IOSurface reuse in the GPU process, or something
like that, but that's a discussion for another day].

[erikchen, 2016/07/20 21:48:01]

Done.

+  std::vector<std::unique_ptr<ScopedResource>> in_use_iosurfaces_;
+  std::vector<std::unique_ptr<ScopedResource>> free_iosurfaces_;
+  size_t iosurface_limit_ = 0;
+
   BoundGeometry bound_geometry_;
   DISALLOW_COPY_AND_ASSIGN(GLRenderer);
 };