Use a direct include of strings headers in ui/, part 3.

ui/views/controls/button/menu_button.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_VIEWS_CONTROLS_BUTTON_MENU_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_MENU_BUTTON_H_
 
 #include <string>
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/time.h"
 #include "ui/gfx/font.h"
 #include "ui/views/background.h"
 #include "ui/views/controls/button/text_button.h"
 
 namespace views {
 
 class MenuButtonListener;
 
 ////////////////////////////////////////////////////////////////////////////////
@@ skipping 79 matching lines @@
   // If non-null the destuctor sets this to true. This is set while the menu is
   // showing and used to detect if the menu was deleted while running.
   bool* destroyed_flag_;
 
   DISALLOW_COPY_AND_ASSIGN(MenuButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_MENU_BUTTON_H_