Implement Discard and EnsureBackbufferCHROMIUM using command buffer instead of IPC.

gpu/command_buffer/service/gles2_cmd_decoder.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file contains the GLES2Decoder class.
 
 #ifndef GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_
 #define GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_
 
 #include <vector>
@@ skipping 27 matching lines @@
   bool multisampling;
   bool driver_bug_workarounds;
 };
 
 // This class implements the AsyncAPIInterface interface, decoding GLES2
 // commands and calling GL.
 class GPU_EXPORT GLES2Decoder : public CommonDecoder {
  public:
   typedef error::Error Error;
   typedef base::Callback<void(int32 id, const std::string& msg)> MsgCallback;
+  typedef base::Callback<void()> DiscardBackbufferCallback;
+  typedef base::Callback<void()> EnsureBackbufferCallback;
 
   // Creates a decoder.
   static GLES2Decoder* Create(ContextGroup* group);
 
   virtual ~GLES2Decoder();
 
   bool debug() const {
     return debug_;
   }
 
@@ skipping 99 matching lines @@
       int level,
       unsigned format,
       unsigned type,
       int width,
       int height,
       bool is_texture_immutable) = 0;
 
   // A callback for messages from the decoder.
   virtual void SetMsgCallback(const MsgCallback& callback) = 0;
 
+  // Called when discard/ensure backbuffer messages are decoded.
+  virtual void SetDiscardBackbufferCallback(
+      const DiscardBackbufferCallback& callback) = 0;
+  virtual void SetEnsureBackbufferCallback(
+      const EnsureBackbufferCallback& callback) = 0;
+
   static bool IsAngle();
 
   // Used for testing only
   static void set_testing_force_is_angle(bool force);
 
  protected:
   GLES2Decoder();
 
  private:
   bool debug_;
   bool log_commands_;
   bool log_synthesized_gl_errors_;
   static bool testing_force_is_angle_;
 
   DISALLOW_COPY_AND_ASSIGN(GLES2Decoder);
 };
 
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_