Add support to delay sending SwapbufferAck as needed.

content/common/gpu/image_transport_surface.h

Index: content/common/gpu/image_transport_surface.h
diff --git a/content/common/gpu/image_transport_surface.h b/content/common/gpu/image_transport_surface.h
index 0c34e86ed7b1bc9283821a662056116497914d16..420690e45b72f39a40f3d637befae333fe63e832 100644
--- a/content/common/gpu/image_transport_surface.h
+++ b/content/common/gpu/image_transport_surface.h
@@ -200,6 +200,7 @@ class PassThroughImageTransportSurface
   // If updated vsync parameters can be determined, send this information to
   // the browser.
   virtual void SendVSyncUpdateIfAvailable();
+  void SwapBuffersCallBack();
 
   ImageTransportHelper* GetHelper() { return helper_.get(); }
 
@@ -207,6 +208,7 @@ class PassThroughImageTransportSurface
   scoped_ptr<ImageTransportHelper> helper_;
   bool did_set_swap_interval_;
   std::vector<ui::LatencyInfo> latency_info_;
+  base::WeakPtrFactory<PassThroughImageTransportSurface> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PassThroughImageTransportSurface);
 };