Replace more ObserverList with base::ObserverList.

ash/wm/dock/docked_window_layout_manager.h

 // Copyright (c) 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_WM_DOCK_DOCKED_WINDOW_LAYOUT_MANAGER_H_
 #define ASH_WM_DOCK_DOCKED_WINDOW_LAYOUT_MANAGER_H_
 
 #include "ash/ash_export.h"
 #include "ash/shelf/shelf_layout_manager_observer.h"
 #include "ash/shell_observer.h"
@@ skipping 306 matching lines @@
   // Used in UMA metrics.
   base::Time last_action_time_;
 
   // Observes shelf for bounds changes.
   scoped_ptr<ShelfWindowObserver> shelf_observer_;
 
   // Widget used to paint a background for the docked area.
   scoped_ptr<DockedBackgroundWidget> background_widget_;
 
   // Observers of dock bounds changes.
-  ObserverList<DockedWindowLayoutManagerObserver> observer_list_;
+  base::ObserverList<DockedWindowLayoutManagerObserver> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(DockedWindowLayoutManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_DOCK_DOCKED_WINDOW_LAYOUT_MANAGER_H_