ui: Cleanup class/struct forward declarations

ui/views/controls/menu/menu_runner_handler.h

 // Copyright 2013 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_MENU_MENU_RUNNER_HANDLER_H_
 #define UI_VIEWS_CONTROLS_MENU_MENU_RUNNER_HANDLER_H_
 
 #include <stdint.h>
 
 namespace views {
 
 class MenuButton;
-class MenuItemView;
 class Widget;
 
 // Used internally by MenuRunner to show the menu. Can be set in tests (see
 // MenuRunnerTestApi) for mocking running of the menu.
 class VIEWS_EXPORT MenuRunnerHandler {
  public:
   virtual ~MenuRunnerHandler() {}
   virtual MenuRunner::RunResult RunMenuAt(Widget* parent,
                                           MenuButton* button,
                                           const gfx::Rect& bounds,
                                           MenuAnchorPosition anchor,
                                           ui::MenuSourceType source_type,
                                           int32_t types) = 0;
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_MENU_MENU_RUNNER_HANDLER_H_