Work around for HDMI audio output rediscovering transistion loss.

ash/system/audio/tray_audio.cc

Index: ash/system/audio/tray_audio.cc
diff --git a/ash/system/audio/tray_audio.cc b/ash/system/audio/tray_audio.cc
index 7260fc01fe82e371a1093413c1b8b1e54fdbb19c..13269bc228a48a9766396fb7a3631cf950511a88 100644
--- a/ash/system/audio/tray_audio.cc
+++ b/ash/system/audio/tray_audio.cc
@@ -138,6 +138,21 @@ void TrayAudio::OnActiveInputNodeChanged() {
   Update();
 }
 
+void TrayAudio::ChangeInternalSpeakerChannelMode() {

[cychiang, 2015/06/26 10:00:21]

I guess you actually move three OnDisplay methods. But what's the purpose of
moving these functions ?

[jennyz, 2015/06/29 20:49:41]

It enables the derived class TrayAudioChromeos to overrides these three
functions.

+  // Swap left/right channel only if it is in Yoga mode.
+  system::TrayAudioDelegate::AudioChannelMode channel_mode =
+      system::TrayAudioDelegate::NORMAL;
+  if (gfx::Display::InternalDisplayId() != gfx::Display::kInvalidDisplayID) {
+    const DisplayInfo& display_info =
+        Shell::GetInstance()->display_manager()->GetDisplayInfo(
+            gfx::Display::InternalDisplayId());
+    if (display_info.GetActiveRotation() == gfx::Display::ROTATE_180)
+      channel_mode = system::TrayAudioDelegate::LEFT_RIGHT_SWAPPED;
+  }
+
+  audio_delegate_->SetInternalSpeakerChannelMode(channel_mode);
+}
+
 void TrayAudio::OnDisplayAdded(const gfx::Display& new_display) {
   if (new_display.id() != gfx::Display::InternalDisplayId())
     return;
@@ -159,21 +174,6 @@ void TrayAudio::OnDisplayMetricsChanged(const gfx::Display& display,
     ChangeInternalSpeakerChannelMode();
 }
 
-void TrayAudio::ChangeInternalSpeakerChannelMode() {
-  // Swap left/right channel only if it is in Yoga mode.
-  system::TrayAudioDelegate::AudioChannelMode channel_mode =
-      system::TrayAudioDelegate::NORMAL;
-  if (gfx::Display::InternalDisplayId() != gfx::Display::kInvalidDisplayID) {
-    const DisplayInfo& display_info =
-        Shell::GetInstance()->display_manager()->GetDisplayInfo(
-            gfx::Display::InternalDisplayId());
-    if (display_info.GetActiveRotation() == gfx::Display::ROTATE_180)
-      channel_mode = system::TrayAudioDelegate::LEFT_RIGHT_SWAPPED;
-  }
-
-  audio_delegate_->SetInternalSpeakerChannelMode(channel_mode);
-}
-
 void TrayAudio::Update() {
   if (tray_view())
       tray_view()->SetVisible(GetInitialVisibility());