ash: Cleanup class/struct forward declarations

ash/common/shelf/shelf_item_delegate.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 ASH_COMMON_SHELF_SHELF_ITEM_DELEGATE_H_
 #define ASH_COMMON_SHELF_SHELF_ITEM_DELEGATE_H_
 
 #include "ash/ash_export.h"
 #include "base/strings/string16.h"
 
 namespace ui {
 class Event;
-class MenuModel;
 }
 
 namespace ash {
 
 class ShelfMenuModel;
 
 // Delegate for the ShelfItem.
 class ASH_EXPORT ShelfItemDelegate {
  public:
   // The return type for the ShelfItemDelegate::ItemSelected method.
@@ skipping 46 matching lines @@
   // Returns true if a tooltip should be shown.
   virtual bool ShouldShowTooltip() = 0;
 
   // Closes all windows associated with this item.
   virtual void Close() = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_SHELF_ITEM_DELEGATE_H_