Ozone: Avoid blocking in Swapbuffer Call.

content/common/gpu/client/command_buffer_proxy_impl.h

Index: content/common/gpu/client/command_buffer_proxy_impl.h
diff --git a/content/common/gpu/client/command_buffer_proxy_impl.h b/content/common/gpu/client/command_buffer_proxy_impl.h
index ea3974029cd1f820de57afbd8895504bed5ed174..45529c8de87f097608cd75ee5f95acb5d63284ce 100644
--- a/content/common/gpu/client/command_buffer_proxy_impl.h
+++ b/content/common/gpu/client/command_buffer_proxy_impl.h
@@ -138,6 +138,11 @@ class CommandBufferProxyImpl
   void SetSwapBuffersCompletionCallback(
       const SwapBuffersCompletionCallback& callback);
 
+  typedef base::Callback<void()>
+      PageFlipCompletionCallback;
+  void SetPageFlipCompletionCallback(
+      const PageFlipCompletionCallback& callback);
+
   // TODO(apatrick): this is a temporary optimization while skia is calling
   // ContentGLContext::MakeCurrent prior to every GL call. It saves returning 6
   // ints redundantly when only the error is needed for the
@@ -168,6 +173,7 @@ class CommandBufferProxyImpl
   void OnSetMemoryAllocation(const gpu::MemoryAllocation& allocation);
   void OnSignalSyncPointAck(uint32 id);
   void OnSwapBuffersCompleted(const std::vector<ui::LatencyInfo>& latency_info);
+  void OnPageFlipCompleted();
 
   // Try to read an updated copy of the state from shared memory.
   void TryUpdateState();
@@ -209,6 +215,7 @@ class CommandBufferProxyImpl
   std::vector<ui::LatencyInfo> latency_info_;
 
   SwapBuffersCompletionCallback swap_buffers_completion_callback_;
+  PageFlipCompletionCallback page_flip_completion_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(CommandBufferProxyImpl);
 };