Add a new audio extension event OnLevelChanged.

chrome/browser/ui/ash/system_tray_delegate_chromeos.cc

Index: chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
diff --git a/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc b/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
index a5e5cc4bd3909d56caeb4d25ea29bdd84f38176a..b34aa94e1c46a778b3d2d7724ca2c0fe3b25882d 100644
--- a/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
+++ b/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
@@ -1213,15 +1213,17 @@ void SystemTrayDelegateChromeOS::InputMethodMenuItemChanged(
 }
 
 // Overridden from CrasAudioHandler::AudioObserver.
-void SystemTrayDelegateChromeOS::OnOutputVolumeChanged() {
-  GetSystemTrayNotifier()->NotifyAudioOutputVolumeChanged();
+void SystemTrayDelegateChromeOS::OnOutputNodeVolumeChanged(uint64_t node_id,
+                                                           int volume) {
+  GetSystemTrayNotifier()->NotifyAudioOutputVolumeChanged(node_id, volume);
 }
 
 void SystemTrayDelegateChromeOS::OnOutputMuteChanged() {
   GetSystemTrayNotifier()->NotifyAudioOutputMuteChanged();
 }
 
-void SystemTrayDelegateChromeOS::OnInputGainChanged() {
+void SystemTrayDelegateChromeOS::OnInputNodeGainChanged(uint64_t /* node_id */,
+                                                        int /* gain */) {
 }
 
 void SystemTrayDelegateChromeOS::OnInputMuteChanged() {