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..7cf378ef840d87ed8dd19f7063471126fecbc4cb 100644
--- a/content/common/gpu/image_transport_surface.h
+++ b/content/common/gpu/image_transport_surface.h
@@ -126,7 +126,7 @@ class ImageTransportHelper
   void SendUpdateVSyncParameters(
       base::TimeTicks timebase, base::TimeDelta interval);
 
-  void SwapBuffersCompleted(const std::vector<ui::LatencyInfo>& latency_info);
+  void SwapBuffersCallBack();
 
   void SetPreemptByFlag(
       scoped_refptr<gpu::PreemptionFlag> preemption_flag);
@@ -134,6 +134,8 @@ class ImageTransportHelper
   // Make the surface's context current.
   bool MakeCurrent();
 
+  void SetLatencyInfo(const std::vector<ui::LatencyInfo>& latency_info);
+
   // Set the default swap interval on the surface.
   static void SetSwapInterval(gfx::GLContext* context);
 
@@ -153,13 +155,12 @@ class ImageTransportHelper
   // Backbuffer resize callback.
   void Resize(gfx::Size size, float scale_factor);
 
-  void SetLatencyInfo(const std::vector<ui::LatencyInfo>& latency_info);
-
   // Weak pointers that point to objects that outlive this helper.
   ImageTransportSurface* surface_;
   GpuChannelManager* manager_;
 
   base::WeakPtr<GpuCommandBufferStub> stub_;
+  std::vector<ui::LatencyInfo> latency_info_;
   int32 route_id_;
   gfx::PluginWindowHandle handle_;
 
@@ -206,7 +207,6 @@ class PassThroughImageTransportSurface
  private:
   scoped_ptr<ImageTransportHelper> helper_;
   bool did_set_swap_interval_;
-  std::vector<ui::LatencyInfo> latency_info_;
 
   DISALLOW_COPY_AND_ASSIGN(PassThroughImageTransportSurface);
 };