Reduce FOR_EACH_OBSERVER usage in extensions

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 <stddef.h>
 #include <stdint.h>
 
 #include "base/callback.h"
@@ skipping 204 matching lines @@
 
 void AudioServiceImpl::OnActiveOutputNodeChanged() {
   NotifyDeviceChanged();
 }
 
 void AudioServiceImpl::OnActiveInputNodeChanged() {
   NotifyDeviceChanged();
 }
 
 void AudioServiceImpl::NotifyDeviceChanged() {
-  FOR_EACH_OBSERVER(AudioService::Observer, observer_list_, OnDeviceChanged());
+  for (auto& observer : observer_list_)
+    observer.OnDeviceChanged();
 }
 
 void AudioServiceImpl::NotifyLevelChanged(uint64_t id, int level) {
-  FOR_EACH_OBSERVER(AudioService::Observer, observer_list_,
-                    OnLevelChanged(base::Uint64ToString(id), level));
+  for (auto& observer : observer_list_)
+    observer.OnLevelChanged(base::Uint64ToString(id), level);
 
   // Notify DeviceChanged event for backward compatibility.
   // TODO(jennyz): remove this code when the old version of hotrod retires.
   NotifyDeviceChanged();
 }
 
 void AudioServiceImpl::NotifyMuteChanged(bool is_input, bool is_muted) {
-  FOR_EACH_OBSERVER(AudioService::Observer, observer_list_,
-                    OnMuteChanged(is_input, is_muted));
+  for (auto& observer : observer_list_)
+    observer.OnMuteChanged(is_input, is_muted);
 
   // Notify DeviceChanged event for backward compatibility.
   // TODO(jennyz): remove this code when the old version of hotrod retires.
   NotifyDeviceChanged();
 }
 
 void AudioServiceImpl::NotifyDevicesChanged() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK(cras_audio_handler_);
 
@@ skipping 16 matching lines @@
         devices[i].is_input
             ? cras_audio_handler_->GetOutputVolumePercentForDevice(
                   devices[i].id)
             : cras_audio_handler_->GetInputGainPercentForDevice(devices[i].id);
     info.stable_device_id.reset(
         new std::string(base::Uint64ToString(devices[i].stable_device_id)));
 
     devices_info_list.push_back(std::move(info));
   }
 
-  FOR_EACH_OBSERVER(AudioService::Observer, observer_list_,
-                    OnDevicesChanged(devices_info_list));
+  for (auto& observer : observer_list_)
+    observer.OnDevicesChanged(devices_info_list);
 
   // 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