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

ash/system/tray/system_tray_notifier.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_TRAY_SYSTEM_TRAY_NOTIFIER_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_NOTIFIER_H_
 
 #include <string>
 #include <vector>
 
 #include "ash/ash_export.h"
+#include "ash/system/audio/audio_observer.h"
 #include "ash/system/bluetooth/bluetooth_observer.h"
 #include "ash/system/chromeos/tray_tracing.h"
 #include "ash/system/date/clock_observer.h"
 #include "ash/system/drive/drive_observer.h"
 #include "ash/system/ime/ime_observer.h"
 #include "ash/system/locale/locale_observer.h"
 #include "ash/system/logout_button/logout_button_observer.h"
 #include "ash/system/session_length_limit/session_length_limit_observer.h"
 #include "ash/system/tray_accessibility.h"
 #include "ash/system/tray_caps_lock.h"
 #include "ash/system/user/update_observer.h"
 #include "ash/system/user/user_observer.h"
 #include "base/observer_list.h"
 #include "base/time/time.h"
 
 #if defined(OS_CHROMEOS)
 #include "ash/system/chromeos/enterprise/enterprise_domain_observer.h"
 #include "ash/system/chromeos/network/network_observer.h"
 #include "ash/system/chromeos/screen_security/screen_capture_observer.h"
 #include "ash/system/chromeos/screen_security/screen_share_observer.h"
 #endif
 
 namespace ash {
 
 #if defined(OS_CHROMEOS)
 class NetworkStateNotifier;
 #endif
 
 class ASH_EXPORT SystemTrayNotifier {
-public:
+ public:
   SystemTrayNotifier();
   ~SystemTrayNotifier();
 
   void AddAccessibilityObserver(AccessibilityObserver* observer);
   void RemoveAccessibilityObserver(AccessibilityObserver* observer);
 
+  void AddAudioObserver(AudioObserver* observer);
+  void RemoveAudioObserver(AudioObserver* observer);
+
   void AddBluetoothObserver(BluetoothObserver* observer);
   void RemoveBluetoothObserver(BluetoothObserver* observer);
 
   void AddCapsLockObserver(CapsLockObserver* observer);
   void RemoveCapsLockObserver(CapsLockObserver* observer);
 
   void AddClockObserver(ClockObserver* observer);
   void RemoveClockObserver(ClockObserver* observer);
 
   void AddDriveObserver(DriveObserver* observer);
@@ skipping 29 matching lines @@
 
   void AddScreenCaptureObserver(ScreenCaptureObserver* observer);
   void RemoveScreenCaptureObserver(ScreenCaptureObserver* observer);
 
   void AddScreenShareObserver(ScreenShareObserver* observer);
   void RemoveScreenShareObserver(ScreenShareObserver* observer);
 #endif
 
   void NotifyAccessibilityModeChanged(
       AccessibilityNotificationVisibility notify);
+  void NotifyAudioOutputVolumeChanged();
+  void NotifyAudioOutputMuteChanged();
+  void NotifyAudioNodesChanged();
+  void NotifyAudioActiveOutputNodeChanged();
+  void NotifyAudioActiveInputNodeChanged();
   void NotifyTracingModeChanged(bool value);
   void NotifyRefreshBluetooth();
   void NotifyBluetoothDiscoveringChanged();
   void NotifyCapsLockChanged(bool enabled, bool search_mapped_to_caps_lock);
   void NotifyRefreshClock();
   void NotifyDateFormatChanged();
   void NotifySystemClockTimeUpdated();
   void NotifyDriveJobUpdated(const DriveOperationStatus& status);
   void NotifyRefreshIME(bool show_message);
   void NotifyShowLoginButtonChanged(bool show_login_button);
@@ skipping 17 matching lines @@
                               const base::string16& helper_name);
   void NotifyScreenShareStop();
 
   NetworkStateNotifier* network_state_notifier() {
     return network_state_notifier_.get();
   }
 #endif
 
  private:
   ObserverList<AccessibilityObserver> accessibility_observers_;
+  ObserverList<AudioObserver> audio_observers_;
   ObserverList<BluetoothObserver> bluetooth_observers_;
   ObserverList<CapsLockObserver> caps_lock_observers_;
   ObserverList<ClockObserver> clock_observers_;
   ObserverList<DriveObserver> drive_observers_;
   ObserverList<IMEObserver> ime_observers_;
   ObserverList<LocaleObserver> locale_observers_;
   ObserverList<LogoutButtonObserver> logout_button_observers_;
   ObserverList<SessionLengthLimitObserver> session_length_limit_observers_;
   ObserverList<TracingObserver> tracing_observers_;
   ObserverList<UpdateObserver> update_observers_;
   ObserverList<UserObserver> user_observers_;
 #if defined(OS_CHROMEOS)
   ObserverList<NetworkObserver> network_observers_;
   ObserverList<EnterpriseDomainObserver> enterprise_domain_observers_;
   ObserverList<ScreenCaptureObserver> screen_capture_observers_;
   ObserverList<ScreenShareObserver> screen_share_observers_;
   scoped_ptr<NetworkStateNotifier> network_state_notifier_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(SystemTrayNotifier);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_NOTIFIER_H_