Add a new audio extension event OnLevelChanged.

chromeos/audio/cras_audio_handler_unittest.cc

Index: chromeos/audio/cras_audio_handler_unittest.cc
diff --git a/chromeos/audio/cras_audio_handler_unittest.cc b/chromeos/audio/cras_audio_handler_unittest.cc
index 574b421abf21e73121b6622b822034a75c38a080..aed4923e1b111e09f37612dc93c7911ab8dc8e47 100644
--- a/chromeos/audio/cras_audio_handler_unittest.cc
+++ b/chromeos/audio/cras_audio_handler_unittest.cc
@@ -259,7 +259,9 @@ class TestObserver : public chromeos::CrasAudioHandler::AudioObserver {
 
   void OnInputMuteChanged() override { ++input_mute_changed_count_; }
 
-  void OnOutputVolumeChanged() override { ++output_volume_changed_count_; }
+  void OnOutputNodeVolumeChanged(uint64 node_id, double volume) override {
+    ++output_volume_changed_count_;
+  }
 
   void OnInputGainChanged() override { ++input_gain_changed_count_; }
 
@@ -1811,7 +1813,7 @@ TEST_F(CrasAudioHandlerTest, SetOutputVolumePercent) {
   cras_audio_handler_->SetOutputVolumePercent(60);
 
   // Verify the output volume is changed to the designated value,
-  // OnOutputVolumeChanged event is fired, and the device volume value
+  // OnOutputNodeVolumeChanged event is fired, and the device volume value
   // is saved the preferences.
   const int kVolume = 60;
   EXPECT_EQ(kVolume, cras_audio_handler_->GetOutputVolumePercent());