Add a new audio extension event OnLevelChanged.

chrome/browser/ui/ash/system_tray_delegate_chromeos.cc

 // Copyright 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 "chrome/browser/ui/ash/system_tray_delegate_chromeos.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 1198 matching lines @@
   GetSystemTrayNotifier()->NotifyRefreshIME();
 }
 
 // Overridden from InputMethodMenuManager::Observer.
 void SystemTrayDelegateChromeOS::InputMethodMenuItemChanged(
     ui::ime::InputMethodMenuManager* manager) {
   GetSystemTrayNotifier()->NotifyRefreshIME();
 }
 
 // Overridden from CrasAudioHandler::AudioObserver.
-void SystemTrayDelegateChromeOS::OnOutputVolumeChanged() {
-  GetSystemTrayNotifier()->NotifyAudioOutputVolumeChanged();
+void SystemTrayDelegateChromeOS::OnOutputNodeVolumeChanged(uint64 node_id,
+                                                           double volume) {
+  GetSystemTrayNotifier()->NotifyAudioOutputVolumeChanged(node_id, volume);
 }
 
 void SystemTrayDelegateChromeOS::OnOutputMuteChanged() {
   GetSystemTrayNotifier()->NotifyAudioOutputMuteChanged();
 }
 
 void SystemTrayDelegateChromeOS::OnInputGainChanged() {
 }
 
 void SystemTrayDelegateChromeOS::OnInputMuteChanged() {
@@ skipping 156 matching lines @@
   LOG(WARNING) << "SystemTrayDelegateChromeOS::GetChildUserMessage call while "
                << "ENABLE_SUPERVISED_USERS undefined.";
   return base::string16();
 }
 
 ash::SystemTrayDelegate* CreateSystemTrayDelegate() {
   return new SystemTrayDelegateChromeOS();
 }
 
 }  // namespace chromeos