Work around for HDMI audio output rediscovering transistion loss.

ash/system/audio/tray_audio.h

Index: ash/system/audio/tray_audio.h
diff --git a/ash/system/audio/tray_audio.h b/ash/system/audio/tray_audio.h
index 9d3b2c94463bb210fae73ef392743d1ee5421a98..caf5760cad0fce65c5cb7c3a665327bbb9d14b4d 100644
--- a/ash/system/audio/tray_audio.h
+++ b/ash/system/audio/tray_audio.h
@@ -31,6 +31,12 @@ class TrayAudio : public TrayImageItem,
   static bool ShowAudioDeviceMenu();
 
  protected:
+  // Overridden from gfx::DisplayObserver.
+  void OnDisplayAdded(const gfx::Display& new_display) override;
+  void OnDisplayRemoved(const gfx::Display& old_display) override;
+  void OnDisplayMetricsChanged(const gfx::Display& display,
+                               uint32_t changed_metrics) override;
+
   virtual void Update();
 
   scoped_ptr<system::TrayAudioDelegate> audio_delegate_;
@@ -59,12 +65,6 @@ class TrayAudio : public TrayImageItem,
   void OnActiveOutputNodeChanged() override;
   void OnActiveInputNodeChanged() override;
 
-  // Overridden from gfx::DisplayObserver.
-  void OnDisplayAdded(const gfx::Display& new_display) override;
-  void OnDisplayRemoved(const gfx::Display& old_display) override;
-  void OnDisplayMetricsChanged(const gfx::Display& display,
-                               uint32_t changed_metrics) override;
-
   void ChangeInternalSpeakerChannelMode();
 
   DISALLOW_COPY_AND_ASSIGN(TrayAudio);