Move low battery notification to Message Center.

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,
     # These files lists are shared with the GN build.
     'ash_sources': [
       'accelerators/accelerator_commands.cc',
@@ skipping 281 matching lines @@
       'system/chromeos/network/tray_network_state_observer.cc',
       'system/chromeos/network/tray_network_state_observer.h',
       'system/chromeos/network/tray_sms.cc',
       'system/chromeos/network/tray_sms.h',
       'system/chromeos/network/tray_vpn.cc',
       'system/chromeos/network/tray_vpn.h',
       'system/chromeos/network/vpn_delegate.cc',
       'system/chromeos/network/vpn_delegate.h',
       'system/chromeos/network/vpn_list_view.cc',
       'system/chromeos/network/vpn_list_view.h',
+      'system/chromeos/power/battery_notification.cc',
+      'system/chromeos/power/battery_notification.h',
       'system/chromeos/power/power_event_observer.cc',
       'system/chromeos/power/power_event_observer.h',
       'system/chromeos/power/power_status.cc',
       'system/chromeos/power/power_status.h',
       'system/chromeos/power/power_status_view.cc',
       'system/chromeos/power/power_status_view.h',
       'system/chromeos/power/tray_power.cc',
       'system/chromeos/power/tray_power.h',
       'system/chromeos/power/video_activity_notifier.cc',
       'system/chromeos/power/video_activity_notifier.h',
@@ skipping 995 matching lines @@
                   '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
                 ],
               }
             ],
           ],
         },
       ],
     }],
   ],
 }