Add missing IWYU message_loop.h includes.

gpu/command_buffer/client/fenced_allocator_test.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.
 
 // This file contains the tests for the FencedAllocator class.
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/memory/aligned_memory.h"
+#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "gpu/command_buffer/client/cmd_buffer_helper.h"
 #include "gpu/command_buffer/client/fenced_allocator.h"
 #include "gpu/command_buffer/service/cmd_buffer_engine.h"
 #include "gpu/command_buffer/service/command_buffer_service.h"
 #include "gpu/command_buffer/service/command_executor.h"
 #include "gpu/command_buffer/service/mocks.h"
 #include "gpu/command_buffer/service/transfer_buffer_manager.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 541 matching lines @@
   EXPECT_LE(token, GetToken());
 
   // Free up everything.
   for (unsigned int i = 0; i < kAllocCount; ++i) {
     allocator_->Free(pointers[i]);
     EXPECT_TRUE(allocator_->CheckConsistency());
   }
 }
 
 }  // namespace gpu