Use a direct include of the message_loop header in ui/, part 1.

ui/aura/root_window_host_x11.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.
 
 #ifndef UI_AURA_ROOT_WINDOW_HOST_X11_H_
 #define UI_AURA_ROOT_WINDOW_HOST_X11_H_
 
 #include <X11/Xlib.h>
 
 #include <vector>
 
 // Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
 #undef RootWindow
 
 #include "base/memory/scoped_ptr.h"
-#include "base/message_loop.h"
+#include "base/message_loop/message_loop.h"
 #include "ui/aura/aura_export.h"
 #include "ui/aura/env_observer.h"
 #include "ui/aura/root_window_host.h"
 #include "ui/base/x/x11_atom_cache.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/gfx/insets.h"
 #include "ui/gfx/rect.h"
 
 namespace ui {
 class MouseEvent;
@@ skipping 124 matching lines @@
 namespace test {
 
 // Set the default value of the override redirect flag used to
 // create a X window for RootWindowHostX11.
 AURA_EXPORT void SetUseOverrideRedirectWindowByDefault(bool override_redirect);
 
 }  // namespace test
 }  // namespace aura
 
 #endif  // UI_AURA_ROOT_WINDOW_HOST_X11_H_