Implement Discard and EnsureBackbufferCHROMIUM using command buffer instead of IPC.

content/common/gpu/client/command_buffer_proxy_impl.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_IMPL_H_
 #define CONTENT_COMMON_GPU_CLIENT_COMMAND_BUFFER_PROXY_IMPL_H_
 #pragma once
 
 #if defined(ENABLE_GPU)
 
@@ skipping 35 matching lines @@
   virtual ~CommandBufferProxyImpl();
 
   // IPC::Channel::Listener implementation:
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   virtual void OnChannelError() OVERRIDE;
 
   // CommandBufferProxy implementation:
   virtual int GetRouteID() const OVERRIDE;
   virtual bool Echo(const base::Closure& callback) OVERRIDE;
   virtual bool SetSurfaceVisible(bool visible) OVERRIDE;
-  virtual bool DiscardBackbuffer() OVERRIDE;
-  virtual bool EnsureBackbuffer() OVERRIDE;
   virtual void SetMemoryAllocationChangedCallback(
       const base::Callback<void(const GpuMemoryAllocationForRenderer&)>&
           callback) OVERRIDE;
   virtual bool SetParent(CommandBufferProxy* parent_command_buffer,
                          uint32 parent_texture_id) OVERRIDE;
   virtual void SetChannelErrorCallback(const base::Closure& callback) OVERRIDE;
   virtual void SetNotifyRepaintTask(const base::Closure& callback) OVERRIDE;
   virtual scoped_refptr<GpuVideoDecodeAcceleratorHost> CreateVideoDecoder(
       media::VideoDecodeAccelerator::Profile profile,
       media::VideoDecodeAccelerator::Client* client) OVERRIDE;
@@ skipping 77 matching lines @@
       memory_allocation_changed_callback_;
 
   GpuConsoleMessageCallback console_message_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(CommandBufferProxyImpl);
 };
 
 #endif  // ENABLE_GPU
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_COMMAND_BUFFER_PROXY_IMPL_H_