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

ash/system/chromeos/audio/tray_audio.h

-// Copyright (c) 2012 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 ASH_SYSTEM_CHROMEOS_AUDIO_TRAY_AUDIO_H_
-#define ASH_SYSTEM_CHROMEOS_AUDIO_TRAY_AUDIO_H_
-
-#include "ash/system/tray/tray_image_item.h"
-#include "chromeos/audio/cras_audio_handler.h"
-
-namespace ash {
-namespace internal {
-
-namespace tray {
-class VolumeView;
-class AudioDetailedView;
-}
-
-class TrayAudio : public TrayImageItem,
-                  public chromeos::CrasAudioHandler::AudioObserver {
- public:
-  explicit TrayAudio(SystemTray* system_tray);
-  virtual ~TrayAudio();
-
- private:
-  // Overridden from TrayImageItem.
-  virtual bool GetInitialVisibility() OVERRIDE;
-
-  // Overridden from SystemTrayItem.
-  virtual views::View* CreateDefaultView(user::LoginStatus status) OVERRIDE;
-  virtual views::View* CreateDetailedView(user::LoginStatus status) OVERRIDE;
-  virtual void DestroyDefaultView() OVERRIDE;
-  virtual void DestroyDetailedView() OVERRIDE;
-  virtual bool ShouldHideArrow() const OVERRIDE;
-  virtual bool ShouldShowShelf() const OVERRIDE;
-
-  // Overridden from chromeos::CrasAudioHandler::AudioObserver.
-  virtual void OnOutputVolumeChanged() OVERRIDE;
-  virtual void OnOutputMuteChanged() OVERRIDE;
-  virtual void OnInputGainChanged() OVERRIDE;
-  virtual void OnInputMuteChanged() OVERRIDE;
-  virtual void OnAudioNodesChanged() OVERRIDE;
-  virtual void OnActiveOutputNodeChanged() OVERRIDE;
-  virtual void OnActiveInputNodeChanged() OVERRIDE;
-
-  void Update();
-
-  tray::VolumeView* volume_view_;
-  tray::AudioDetailedView* audio_detail_;
-
-  // True if VolumeView should be created for accelerator pop up;
-  // Otherwise, it should be created for detailed view in ash tray bubble.
-  bool pop_up_volume_view_;
-
-  DISALLOW_COPY_AND_ASSIGN(TrayAudio);
-};
-
-}  // namespace internal
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_CHROMEOS_AUDIO_TRAY_AUDIO_H_