Implement Discard and EnsureBackbufferCHROMIUM using command buffer instead of IPC.

content/common/gpu/client/content_gl_context.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 API is consistent with other OpenGL setup APIs like window's WGL
 // and pepper's PGL. This API is used to manage OpenGL ContentGLContexts in the
 // Chrome renderer process in a way that is consistent with other platforms.
 
 #ifndef CONTENT_COMMON_GPU_CLIENT_RENDERER_GL_CONTEXT_H_
 #define CONTENT_COMMON_GPU_CLIENT_RENDERER_GL_CONTEXT_H_
@@ skipping 146 matching lines @@
   // by the parent ContentGLContext.
   bool SwapBuffers();
 
   // Run the task once the channel has been flushed. Takes care of deleting the
   // task whether the echo succeeds or not.
   bool Echo(const base::Closure& task);
 
   // Sends an IPC message with the new state of surface visibility
   bool SetSurfaceVisible(bool visibility);
 
-  bool DiscardBackbuffer();
-  bool EnsureBackbuffer();
-
   // Register a callback to invoke whenever we recieve a new memory allocation.
   void SetMemoryAllocationChangedCallback(
       const base::Callback<void(const GpuMemoryAllocationForRenderer&)>&
           callback);
 
   // Allows direct access to the GLES2 implementation so a ContentGLContext
   // can be used without making it current.
   gpu::gles2::GLES2Implementation* GetImplementation();
 
   // Return the current error.
@@ skipping 36 matching lines @@
   gpu::gles2::GLES2CmdHelper* gles2_helper_;
   gpu::TransferBuffer* transfer_buffer_;
   gpu::gles2::GLES2Implementation* gles2_implementation_;
   Error last_error_;
   int frame_number_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentGLContext);
 };
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_RENDERER_GL_CONTEXT_H_