Update NetworkStateNotifier to use 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,
     'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/chrome',
   },
   'includes': [
@@ skipping 209 matching lines @@
         'system/chromeos/managed/tray_locally_managed_user.h',
         'system/chromeos/managed/tray_locally_managed_user.cc',
         'system/chromeos/network/network_connect.cc',
         'system/chromeos/network/network_connect.h',
         'system/chromeos/network/network_detailed_view.h',
         'system/chromeos/network/network_icon.cc',
         'system/chromeos/network/network_icon.h',
         'system/chromeos/network/network_icon_animation.cc',
         'system/chromeos/network/network_icon_animation.h',
         'system/chromeos/network/network_icon_animation_observer.h',
-        'system/chromeos/network/network_observer.cc',
         'system/chromeos/network/network_observer.h',
         'system/chromeos/network/network_state_list_detailed_view.cc',
         'system/chromeos/network/network_state_list_detailed_view.h',
         'system/chromeos/network/network_state_notifier.cc',
         'system/chromeos/network/network_state_notifier.h',
-        'system/chromeos/network/network_tray_delegate.h',
         'system/chromeos/network/tray_network.cc',
         'system/chromeos/network/tray_network.h',
         '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/power/power_status.cc',
         'system/chromeos/power/power_status.h',
@@ skipping 676 matching lines @@
             'shell/cocoa/app-Info.plist',
           ],
           'xcode_settings': {
             'INFOPLIST_FILE': 'shell/cocoa/app-Info.plist',
           },
         }],
       ],
     },
   ],
 }