Enable the volume slider in Ash for windows.

ash/ash.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
     'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/chrome',
   },
   'includes': [
@@ skipping 435 matching lines @@
         'system/user/login_status.cc',
         'system/user/login_status.h',
         'system/user/tray_user.cc',
         'system/user/tray_user.h',
         'system/user/tray_user_separator.cc',
         'system/user/tray_user_separator.h',
         'system/user/update_observer.h',
         'system/user/user_observer.h',
         'system/web_notification/web_notification_tray.cc',
         'system/web_notification/web_notification_tray.h',
+        'system/win/audio/tray_audio_delegate_win.cc',
+        'system/win/audio/tray_audio_delegate_win.h',
+        'system/win/audio/tray_audio_win.cc',
+        'system/win/audio/tray_audio_win.h',
         'touch/touch_hud_debug.cc',
         'touch/touch_hud_debug.h',
         'touch/touch_hud_projection.cc',
         'touch/touch_hud_projection.h',
         'touch/touch_observer_hud.cc',
         'touch/touch_observer_hud.h',
         'touch/touch_uma.cc',
         'touch/touch_uma.h',
         'volume_control_delegate.h',
         'wm/app_list_controller.cc',
@@ skipping 646 matching lines @@
             },
           },
           'dependencies': [
             '../sandbox/sandbox.gyp:sandbox',
           ],
         }],
       ],
     },
   ],
 }