Add EncodeBackbufferCHROMIUM support to GLES2 command stream

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 b7978756b2b076548b0316c56e776af398eed7b1..1f26eb12594a984a2653c3d8ff200d0b2db025e5 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.h
@@ -89,6 +89,7 @@ class GPU_EXPORT GLES2Decoder : public base::SupportsWeakPtr<GLES2Decoder>,
   typedef error::Error Error;
   typedef base::Callback<void(int32 id, const std::string& msg)> MsgCallback;
   typedef base::Callback<bool(uint32 id)> WaitSyncPointCallback;
+  typedef base::Callback<void(void)> EncodeBackbufferCallback;
 
   // Creates a decoder.
   static GLES2Decoder* Create(ContextGroup* group);
@@ -286,6 +287,11 @@ class GPU_EXPORT GLES2Decoder : public base::SupportsWeakPtr<GLES2Decoder>,
   virtual void SetWaitSyncPointCallback(
       const WaitSyncPointCallback& callback) = 0;
 
+  // Sets the callback for encoding a backbuffer. The callback schedules the
+  // backbuffer to be encoded.
+  virtual void SetEncodeBackbufferCallback(
+      const EncodeBackbufferCallback& callback) = 0;
+
   virtual uint32 GetTextureUploadCount() = 0;
   virtual base::TimeDelta GetTotalTextureUploadTime() = 0;
   virtual base::TimeDelta GetTotalProcessingCommandsTime() = 0;