Make WaitSyncPoint go through command buffers.

gpu/command_buffer/service/gles2_cmd_decoder.h

Index: gpu/command_buffer/service/gles2_cmd_decoder.h
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.h b/gpu/command_buffer/service/gles2_cmd_decoder.h
index e4f0b3538b96126e8921e9831f01a90ace80dea9..a91926eea0d2cc181500da537aba348d2940a273 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.h
@@ -53,6 +53,7 @@ class GPU_EXPORT GLES2Decoder : public base::SupportsWeakPtr<GLES2Decoder>,
  public:
   typedef error::Error Error;
   typedef base::Callback<void(int32 id, const std::string& msg)> MsgCallback;
+  typedef base::Callback<bool(uint32 id)> WaitSyncPointCallback;
 
   // Creates a decoder.
   static GLES2Decoder* Create(ContextGroup* group);
@@ -190,6 +191,11 @@ class GPU_EXPORT GLES2Decoder : public base::SupportsWeakPtr<GLES2Decoder>,
   // A callback for messages from the decoder.
   virtual void SetMsgCallback(const MsgCallback& callback) = 0;
 
+  // Sets the callback for waiting on a sync point. The callback returns the
+  // scheduling status (i.e. true if the channel is still scheduled).
+  virtual void SetWaitSyncPointCallback(
+      const WaitSyncPointCallback& callback) = 0;
+
   virtual uint32 GetTextureUploadCount() = 0;
   virtual base::TimeDelta GetTotalTextureUploadTime() = 0;
   virtual base::TimeDelta GetTotalProcessingCommandsTime() = 0;