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

ash/ash_switches.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_ASH_SWITCHES_H_
 #define ASH_ASH_SWITCHES_H_
 
 #include "ash/ash_export.h"
 
 #include "build/build_config.h"
@@ skipping 83 matching lines @@
 
 // Returns true if multiple user icons are allowed in the tray.
 ASH_EXPORT bool UseMultiUserTray();
 
 // Returns true if overview mode should be activated for window switching.
 ASH_EXPORT bool UseOverviewMode();
 
 // Returns true if docked windows feature is enabled.
 ASH_EXPORT bool UseDockedWindows();
 
-#if defined(OS_CHROMEOS)
 // Returns true if we should show the audio device switching UI.
 ASH_EXPORT bool ShowAudioDeviceMenu();
 
+#if defined(OS_CHROMEOS)
 // Returns true if a notification should appear when a low-power USB charger
 // is connected.
 ASH_EXPORT bool UseUsbChargerNotification();
 #endif
 
 }  // namespace switches
 }  // namespace ash
 
 #endif  // ASH_ASH_SWITCHES_H_