mix-blend-mode implementation for accelerated layers

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 def9a259d5b680bcd213b61a1a9e49d51c04575b..d5827695faf5bf8a19918ff180e2a5f86b3b8fa7 100644
--- a/cc/output/gl_renderer.h
+++ b/cc/output/gl_renderer.h
@@ -151,11 +151,12 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
                             const CheckerboardDrawQuad* quad);
   void DrawDebugBorderQuad(const DrawingFrame* frame,
                            const DebugBorderDrawQuad* quad);
-  scoped_ptr<ScopedResource> DrawBackgroundFilters(
+  scoped_ptr<ScopedResource> GetBackgroundWithFilters(
       DrawingFrame* frame,
       const RenderPassDrawQuad* quad,
       const gfx::Transform& contents_device_transform,
-      const gfx::Transform& contents_device_transformInverse);
+      const gfx::Transform& contents_device_transformInverse,
+      bool* background_changed);
   void DrawRenderPassQuad(DrawingFrame* frame, const RenderPassDrawQuad* quad);
   void DrawSolidColorQuad(const DrawingFrame* frame,
                           const SolidColorDrawQuad* quad);