Implement Discard and EnsureBackbufferCHROMIUM using command buffer instead of IPC.

gpu/command_buffer/common/gles2_cmd_ids_autogen.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 is auto-generated from
 // gpu/command_buffer/build_gles2_cmd_buffer.py
 // DO NOT EDIT!
 
 #ifndef GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_IDS_AUTOGEN_H_
 #define GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_IDS_AUTOGEN_H_
@@ skipping 203 matching lines @@
   OP(GetMultipleIntegervCHROMIUM)                              /* 457 */ \
   OP(GetProgramInfoCHROMIUM)                                   /* 458 */ \
   OP(CreateStreamTextureCHROMIUM)                              /* 459 */ \
   OP(DestroyStreamTextureCHROMIUM)                             /* 460 */ \
   OP(GetTranslatedShaderSourceANGLE)                           /* 461 */ \
   OP(PostSubBufferCHROMIUM)                                    /* 462 */ \
   OP(TexImageIOSurface2DCHROMIUM)                              /* 463 */ \
   OP(DrawArraysInstancedANGLE)                                 /* 464 */ \
   OP(DrawElementsInstancedANGLE)                               /* 465 */ \
   OP(VertexAttribDivisorANGLE)                                 /* 466 */ \
+  OP(DiscardBackbufferCHROMIUM)                                /* 467 */ \
+  OP(EnsureBackbufferCHROMIUM)                                 /* 468 */ \
 
 enum CommandId {
   kStartPoint = cmd::kLastCommonId,  // All GLES2 commands start after this.
 #define GLES2_CMD_OP(name) k ## name,
   GLES2_COMMAND_LIST(GLES2_CMD_OP)
 #undef GLES2_CMD_OP
   kNumCommands
 };
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_IDS_AUTOGEN_H_