Remove unused ShelfModelObserver::ShelfStatusChanged()

ash/shelf/shelf_model_observer.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_SHELF_SHELF_MODEL_OBSERVER_H_
 #define ASH_SHELF_SHELF_MODEL_OBSERVER_H_
 
 #include "ash/ash_export.h"
 #include "ash/shelf/shelf_item_types.h"
 
@@ skipping 11 matching lines @@
   virtual void ShelfItemRemoved(int index, ShelfID id) = 0;
 
   // Invoked after an item has been moved. See ShelfModel::Move() for details
   // of the arguments.
   virtual void ShelfItemMoved(int start_index, int target_index) = 0;
 
   // Invoked when the state of an item changes. |old_item| is the item
   // before the change.
   virtual void ShelfItemChanged(int index, const ShelfItem& old_item) = 0;
 
-  // Invoked when shelf status is changed.
-  virtual void ShelfStatusChanged() = 0;
-
  protected:
   virtual ~ShelfModelObserver() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_SHELF_MODEL_OBSERVER_H_