Refactor the TrayAudio code so that it can be used by other platforms.

chromeos/audio/cras_audio_handler.h

 // Copyright (c) 2013 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.
 
 #ifndef CHROMEOS_AUDIO_CRAS_AUDIO_HANDLER_H_
 #define CHROMEOS_AUDIO_CRAS_AUDIO_HANDLER_H_
 
 #include <queue>
 
 #include "base/basictypes.h"
@@ skipping 81 matching lines @@
 
   // Returns true if audio input is muted.
   virtual bool IsInputMuted();
 
   // Returns true if audio input is muted for a device.
   virtual bool IsInputMutedForDevice(uint64 device_id);
 
   // Returns true if the output volume is below the default mute volume level.
   virtual bool IsOutputVolumeBelowDefaultMuteLvel();
 
+  // Returns volume level in 0-100% range at which the volume should be muted.
+  virtual int GetOutputDefaultVolumeMuteThreshold();
+
   // Gets volume level in 0-100% range (0 being pure silence) for the current
   // active node.
   virtual int GetOutputVolumePercent();
 
   // Gets volume level in 0-100% range (0 being pure silence) for a device.
   virtual int GetOutputVolumePercentForDevice(uint64 device_id);
 
   // Gets gain level in 0-100% range (0 being pure silence) for the current
   // active node.
   virtual int GetInputGainPercent();
@@ skipping 156 matching lines @@
 
   // Failures are not logged at startup, since CRAS may not be running yet.
   bool log_errors_;
 
   DISALLOW_COPY_AND_ASSIGN(CrasAudioHandler);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_AUDIO_CRAS_AUDIO_HANDLER_H_