Remove GenMailboxCHROMIUM command

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // 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.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 15757 matching lines @@
                                       GLenum internal_format,
                                       GLsizei width,
                                       GLsizei height,
                                       GLsizei depth) {
   TRACE_EVENT2("gpu", "GLES2DecoderImpl::DoTexStorage3D",
       "widthXheight", width * height, "depth", depth);
   TexStorageImpl(target, levels, internal_format, width, height, depth,
                  ContextState::k3D, "glTexStorage3D");
 }
 
-error::Error GLES2DecoderImpl::HandleGenMailboxCHROMIUM(
-    uint32_t immediate_data_size,
-    const void* cmd_data) {
-  return error::kUnknownCommand;
-}
-
 void GLES2DecoderImpl::DoProduceTextureCHROMIUM(GLenum target,
                                                 const GLbyte* data) {
   TRACE_EVENT2("gpu", "GLES2DecoderImpl::DoProduceTextureCHROMIUM",
       "context", logger_.GetLogPrefix(),
       "mailbox[0]", static_cast<unsigned char>(data[0]));
 
   TextureRef* texture_ref = texture_manager()->GetTextureInfoForTarget(
       &state_, target);
   ProduceTextureRef("glProduceTextureCHROMIUM", false, texture_ref, target,
                     data);
@@ skipping 1919 matching lines @@
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "base/macros.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu