Work around for HDMI audio output rediscovering transistion loss.

ash/system/chromeos/audio/tray_audio_delegate_chromeos.cc

Index: ash/system/chromeos/audio/tray_audio_delegate_chromeos.cc
diff --git a/ash/system/chromeos/audio/tray_audio_delegate_chromeos.cc b/ash/system/chromeos/audio/tray_audio_delegate_chromeos.cc
index fb1532fe37d177f9c42339ada7980d8f309fc7d2..daa3453ff51ae92b69dd294e800c38621160af98 100644
--- a/ash/system/chromeos/audio/tray_audio_delegate_chromeos.cc
+++ b/ash/system/chromeos/audio/tray_audio_delegate_chromeos.cc
@@ -66,5 +66,11 @@ void TrayAudioDelegateChromeOs::SetInternalSpeakerChannelMode(
       mode == LEFT_RIGHT_SWAPPED);
 }
 
+void TrayAudioDelegateChromeOs::SetActiveHDMIOutoutRediscoveringIfNecessary(
+    bool force_rediscovering) {
+  CrasAudioHandler::Get()->SetActiveHDMIOutoutRediscoveringIfNecessary(
+      force_rediscovering);
+}
+
 }  // namespace system
 }  // namespace ash