Ash: Fix browser icon menu model lifetime

ash/shelf/shelf_view.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 ASH_SHELF_SHELF_VIEW_H_
 #define ASH_SHELF_SHELF_VIEW_H_
 
 #include <utility>
 #include <vector>
 
@@ skipping 351 matching lines @@
   gfx::Point drag_origin_;
 
   // Index |drag_view_| was initially at.
   int start_drag_index_;
 
   // Used for the context menu of a particular item.
   ShelfID context_menu_id_;
 
   scoped_ptr<views::FocusSearch> focus_search_;
 
-  scoped_ptr<ui::MenuModel> list_menu_model_;
-
   scoped_ptr<ui::MenuModel> context_menu_model_;
 
   scoped_ptr<views::MenuRunner> launcher_menu_runner_;
 
   ObserverList<ShelfIconObserver> observers_;
 
   // Amount content is inset on the left edge (or top edge for vertical
   // alignment).
   int leading_inset_;
 
@@ skipping 57 matching lines @@
 
   // True when ripped item from overflow bubble is entered into Shelf.
   bool dragged_off_from_overflow_to_shelf_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_SHELF_VIEW_H_