Fix the UI issue for showing output muted in ash tray after the device wakes up with hdmi output re…

ash/system/audio/audio_observer.h

Index: ash/system/audio/audio_observer.h
diff --git a/ash/system/audio/audio_observer.h b/ash/system/audio/audio_observer.h
index 3b94ebc8b5f6e9147226ddac9c3961fa328d7972..7a18e17d56845bfdc195f1ebbdaa2f27c7902c40 100644
--- a/ash/system/audio/audio_observer.h
+++ b/ash/system/audio/audio_observer.h
@@ -19,7 +19,12 @@ class AudioObserver {
   virtual void OnOutputNodeVolumeChanged(uint64_t node_id, double volume) = 0;
 
   // Called when output mute state changed.
-  virtual void OnOutputMuteChanged(bool mute_on) = 0;
+  // |mute_on|: True if output is muted.
+  // |system_adjust|: True if the mute state is adjusted by the system
+  // automatically, UI should be consistent with the system's mute state,
+  // but it should not be too loud, e.g., the volume pop up window should not
+  // be triggered.
+  virtual void OnOutputMuteChanged(bool mute_on, bool system_adjust) = 0;
 
   // Called when audio nodes changed.
   virtual void OnAudioNodesChanged() = 0;