ash uber tray: Update the volume icon for various levels of volumes.

ash/system/audio/tray_volume.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_AUDIO_TRAY_VOLUME_H_
 #define ASH_SYSTEM_AUDIO_TRAY_VOLUME_H_
 #pragma once
 
 #include "ash/system/audio/audio_controller.h"
 #include "ash/system/tray/system_tray_item.h"
 #include "base/memory/scoped_ptr.h"
 
-namespace views {
-class ImageView;
-}
+namespace ash {
+namespace internal {
 
 namespace tray {
 class VolumeView;
 }
 
-namespace ash {
-namespace internal {
-
 class TrayVolume : public SystemTrayItem,
                    public AudioController {
  public:
   TrayVolume();
   virtual ~TrayVolume();
 
  private:
-  // Overridden from SystemTrayItem
+  // Overridden from SystemTrayItem.
   virtual views::View* CreateTrayView() OVERRIDE;
   virtual views::View* CreateDefaultView() OVERRIDE;
   virtual views::View* CreateDetailedView() OVERRIDE;
   virtual void DestroyTrayView() OVERRIDE;
   virtual void DestroyDefaultView() OVERRIDE;
   virtual void DestroyDetailedView() OVERRIDE;
 
   // Overridden from AudioController.
   virtual void OnVolumeChanged(float percent) OVERRIDE;
 
   scoped_ptr<tray::VolumeView> volume_view_;
-  scoped_ptr<views::ImageView> tray_view_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayVolume);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_AUDIO_TRAY_VOLUME_H_