cc: Async readback.

cc/output/direct_renderer.h

Index: cc/output/direct_renderer.h
diff --git a/cc/output/direct_renderer.h b/cc/output/direct_renderer.h
index bb3095a77a119352bb790237a5b25bc6a7f63617..1d053553ed8a1e710471d20deb077a18d4eb1e34 100644
--- a/cc/output/direct_renderer.h
+++ b/cc/output/direct_renderer.h
@@ -92,7 +92,8 @@ class CC_EXPORT DirectRenderer : public Renderer {
   static gfx::Size RenderPassTextureSize(const RenderPass* render_pass);
   static GLenum RenderPassTextureFormat(const RenderPass* render_pass);
 
-  void DrawRenderPass(DrawingFrame* frame, const RenderPass* render_pass);
+  void DrawRenderPass(DrawingFrame* frame,
+                      const RenderPass* render_pass);
   bool UseRenderPass(DrawingFrame* frame, const RenderPass* render_pass);
 
   virtual void BindFramebufferToOutputSurface(DrawingFrame* frame) = 0;
@@ -109,6 +110,8 @@ class CC_EXPORT DirectRenderer : public Renderer {
   virtual bool FlippedFramebuffer() const = 0;
   virtual void EnsureScissorTestEnabled() = 0;
   virtual void EnsureScissorTestDisabled() = 0;
+  virtual void CopyCurrentRenderPassToBitmap(DrawingFrame* frame,
+                                             SkBitmap* bitmap) = 0;
 
   ScopedPtrHashMap<RenderPass::Id, CachedResource> render_pass_textures_;
   ResourceProvider* resource_provider_;