Replace more ObserverList with base::ObserverList.

ui/base/models/list_model.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 UI_BASE_MODELS_LIST_MODEL_H_
 #define UI_BASE_MODELS_LIST_MODEL_H_
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 116 matching lines @@
   typename ScopedVector<ItemType>::const_iterator begin() const {
     return items_.begin();
   }
   typename ScopedVector<ItemType>::iterator end() { return items_.end(); }
   typename ScopedVector<ItemType>::const_iterator end() const {
     return items_.end();
   }
 
  private:
   ScopedVector<ItemType> items_;
-  ObserverList<ListModelObserver> observers_;
+  base::ObserverList<ListModelObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ListModel<ItemType>);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_MODELS_LIST_MODEL_H_