Work around for HDMI audio output rediscovering transistion loss.

ash/system/win/audio/tray_audio_delegate_win.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/system/win/audio/tray_audio_delegate_win.h"
 
 #include <audiopolicy.h>
 #include <cmath>
 
 #include "media/audio/win/core_audio_util_win.h"
@@ skipping 78 matching lines @@
     return;
 
   float volume_level = static_cast<float>(level) / 100.0f;
   volume_control->SetMasterVolume(volume_level, NULL);
 }
 
 void TrayAudioDelegateWin::SetInternalSpeakerChannelMode(
     AudioChannelMode mode) {
 }
 
+void TrayAudioDelegateWin::SetActiveHDMIOutoutRediscoveringIfNecessary(
+    bool force_rediscovering) {
+}
+
 ScopedComPtr<ISimpleAudioVolume>
 TrayAudioDelegateWin::CreateDefaultVolumeControl() {
   ScopedComPtr<ISimpleAudioVolume> volume_control;
   ScopedComPtr<IAudioSessionManager> session_manager;
 
   ScopedComPtr<IMMDevice> device =
       media::CoreAudioUtil::CreateDefaultDevice(eRender, eConsole);
   if (!device.get() ||
       FAILED(device->Activate(__uuidof(IAudioSessionManager), CLSCTX_ALL, NULL,
                               session_manager.ReceiveVoid()))) {
     return volume_control;
   }
 
   session_manager->GetSimpleAudioVolume(NULL, FALSE,
       volume_control.Receive());
 
   return volume_control;
 }
 
 }  // namespace system
 }  // namespace ash