Remove GenMailboxCHROMIUM command

gpu/command_buffer/service/gles2_cmd_decoder_passthrough_handlers.cc

 // Copyright (c) 2016 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_passthrough.h"
 
 namespace gpu {
 namespace gles2 {
 
 // Custom Handlers
@@ skipping 1493 matching lines @@
       *static_cast<const gles2::cmds::VertexAttribDivisorANGLE*>(cmd_data);
   GLuint index = static_cast<GLuint>(c.index);
   GLuint divisor = static_cast<GLuint>(c.divisor);
   error::Error error = DoVertexAttribDivisorANGLE(index, divisor);
   if (error != error::kNoError) {
     return error;
   }
   return error::kNoError;
 }
 
-error::Error GLES2DecoderPassthroughImpl::HandleGenMailboxCHROMIUM(
-    uint32_t immediate_data_size,
-    const void* cmd_data) {
-  const gles2::cmds::GenMailboxCHROMIUM& c =
-      *static_cast<const gles2::cmds::GenMailboxCHROMIUM*>(cmd_data);
-  (void)c;
-  return error::kUnknownCommand;
-}
-
 error::Error
 GLES2DecoderPassthroughImpl::HandleBindUniformLocationCHROMIUMBucket(
     uint32_t immediate_data_size,
     const void* cmd_data) {
   const gles2::cmds::BindUniformLocationCHROMIUMBucket& c =
       *static_cast<const gles2::cmds::BindUniformLocationCHROMIUMBucket*>(
           cmd_data);
   GLuint program = static_cast<GLuint>(c.program);
   GLint location = static_cast<GLint>(c.location);
   Bucket* bucket = GetBucket(c.name_bucket_id);
@@ skipping 853 matching lines @@
   }
   error::Error error = DoGetFragDataIndexEXT(program, name_str.c_str(), index);
   if (error != error::kNoError) {
     return error;
   }
   return error::kNoError;
 }
 
 }  // namespace gles2
 }  // namespace gpu