Add missing IWYU message_loop.h includes.

extensions/shell/browser/shell_desktop_controller_aura.cc

 // Copyright 2014 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 "extensions/shell/browser/shell_desktop_controller_aura.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
+#include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "extensions/browser/app_window/app_window.h"
 #include "extensions/browser/app_window/native_app_window.h"
 #include "extensions/shell/browser/input_method_event_handler.h"
 #include "extensions/shell/browser/shell_app_delegate.h"
 #include "extensions/shell/browser/shell_app_window_client.h"
 #include "extensions/shell/browser/shell_screen.h"
 #include "extensions/shell/common/switches.h"
@@ skipping 365 matching lines @@
   if (displays.empty())
     return gfx::Size();
   const display::DisplayMode* mode = displays[0]->current_mode();
   return mode ? mode->size() : gfx::Size();
 #else
   return gfx::Size();
 #endif
 }
 
 }  // namespace extensions