ash: Cleanup class/struct forward declarations

ash/common/shelf/overflow_bubble.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_OVERFLOW_BUBBLE_H_
 #define ASH_COMMON_SHELF_OVERFLOW_BUBBLE_H_
 
 #include "base/macros.h"
 #include "ui/views/pointer_watcher.h"
 #include "ui/views/widget/widget_observer.h"
 
 namespace ui {
 class PointerEvent;
 }
 
-namespace views {
-class View;
-}
-
 namespace ash {
 class OverflowBubbleView;
 class OverflowButton;
 class ShelfView;
 class WmShelf;
 
 // OverflowBubble shows shelf items that won't fit on the main shelf in a
 // separate bubble.
 class OverflowBubble : public views::PointerWatcher,
                        public views::WidgetObserver {
@@ skipping 30 matching lines @@
 
   // ShelfView containing the overflow items. Owned by |bubble_|.
   ShelfView* shelf_view_;
 
   DISALLOW_COPY_AND_ASSIGN(OverflowBubble);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_OVERFLOW_BUBBLE_H_