ui: Cleanup class/struct forward declarations

ui/views/controls/menu/menu_runner_impl_interface.h

 // 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.
 
 #ifndef UI_VIEWS_CONTROLS_MENU_MENU_RUNNER_IMPL_INTERFACE_H_
 #define UI_VIEWS_CONTROLS_MENU_MENU_RUNNER_IMPL_INTERFACE_H_
 
 #include <stdint.h>
 
 #include "base/callback_forward.h"
 #include "ui/views/controls/menu/menu_runner.h"
 
 namespace views {
 
-class MenuItemView;
-
 namespace internal {
 
 // An abstract interface for menu runner implementations.
 // Invoke Release() to destroy. Release() deletes immediately if the menu isn't
 // showing. If the menu is showing Release() cancels the menu and when the
 // nested RunMenuAt() call returns deletes itself and the menu.
 class MenuRunnerImplInterface {
  public:
   // Creates a concrete instance for running |menu_model|.
   // |run_types| is a bitmask of MenuRunner::RunTypes.
@@ skipping 24 matching lines @@
 
  protected:
   // Call Release() to delete.
   virtual ~MenuRunnerImplInterface() {}
 };
 
 }  // namespace internal
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_MENU_MENU_RUNNER_IMPL_INTERFACE_H_