Replace more ObserverList with base::ObserverList.

components/update_client/update_client_internal.h

 // Copyright 2015 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 COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_INTERNAL_H_
 #define COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_INTERNAL_H_
 
 #include "components/update_client/update_client.h"
 
 #include <queue>
@@ skipping 57 matching lines @@
   // Contains the tasks that are queued up.
   std::queue<Task*> task_queue_;
 
   // Contains all tasks in progress.
   std::set<Task*> tasks_;
 
   // TODO(sorin): try to make the ping manager an observer of the service.
   scoped_ptr<PingManager> ping_manager_;
   scoped_ptr<UpdateEngine> update_engine_;
 
-  ObserverList<Observer> observer_list_;
+  base::ObserverList<Observer> observer_list_;
 
   // Used to post responses back to the main thread.
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(UpdateClientImpl);
 };
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_INTERNAL_H_