Implement Discard and EnsureBackbufferCHROMIUM using command buffer instead of IPC.

content/common/gpu/client/command_buffer_proxy.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.
 
 #ifndef CONTENT_COMMON_GPU_CLIENT_COMMAND_BUFFER_PROXY_H_
 #define CONTENT_COMMON_GPU_CLIENT_COMMAND_BUFFER_PROXY_H_
 #pragma once
 
 #if defined(ENABLE_GPU)
 
@@ skipping 21 matching lines @@
 
   virtual int GetRouteID() const = 0;
 
   // Invoke the task when the channel has been flushed. Takes care of deleting
   // the task whether the echo succeeds or not.
   virtual bool Echo(const base::Closure& callback) = 0;
 
   // Sends an IPC message with the new state of surface visibility.
   virtual bool SetSurfaceVisible(bool visible) = 0;
 
-  virtual bool DiscardBackbuffer() = 0;
-  virtual bool EnsureBackbuffer() = 0;
-
   // Register a callback to invoke whenever we recieve a new memory allocation.
   virtual void SetMemoryAllocationChangedCallback(
       const base::Callback<void(const GpuMemoryAllocationForRenderer&)>&
           callback) = 0;
 
   // Reparent a command buffer. TODO(apatrick): going forward, the notion of
   // the parent / child relationship between command buffers is going away in
   // favor of the notion of surfaces that can be drawn to in one command buffer
   // and bound as a texture in any other.
   virtual bool SetParent(CommandBufferProxy* parent_command_buffer,
@@ skipping 18 matching lines @@
   virtual void SetOnConsoleMessageCallback(
       const GpuConsoleMessageCallback& callback) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CommandBufferProxy);
 };
 
 #endif  // ENABLE_GPU
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_COMMAND_BUFFER_PROXY_H_