Replace more ObserverList with base::ObserverList.

extensions/browser/api/audio/audio_service_chromeos.cc

 // 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.
 
 #include "extensions/browser/api/audio/audio_service.h"
 
 #include "base/callback.h"
 #include "base/memory/weak_ptr.h"
 #include "base/strings/string_number_conversions.h"
 #include "chromeos/audio/audio_device.h"
@@ skipping 39 matching lines @@
  private:
   void NotifyDeviceChanged();
   void NotifyLevelChanged(uint64_t id, int level);
   void NotifyMuteChanged(bool is_input, bool is_muted);
   void NotifyDevicesChanged();
 
   bool FindDevice(uint64_t id, chromeos::AudioDevice* device);
   uint64_t GetIdFromStr(const std::string& id_str);
 
   // List of observers.
-  ObserverList<AudioService::Observer> observer_list_;
+  base::ObserverList<AudioService::Observer> observer_list_;
 
   chromeos::CrasAudioHandler* cras_audio_handler_;
 
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate the weak pointers before any other members are destroyed.
   base::WeakPtrFactory<AudioServiceImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioServiceImpl);
 };
 
@@ skipping 210 matching lines @@
   // Notify DeviceChanged event for backward compatibility.
   // TODO(jennyz): remove this code when the old version of hotrod retires.
   NotifyDeviceChanged();
 }
 
 AudioService* AudioService::CreateInstance() {
   return new AudioServiceImpl;
 }
 
 }  // namespace extensions