Add countdown when session time is limited

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 197 matching lines @@
         'system/logout_button/tray_logout_button.h',
         'system/monitor/tray_monitor.cc',
         'system/monitor/tray_monitor.h',
         'system/power/power_status_observer.h',
         'system/power/power_status_view.cc',
         'system/power/power_status_view.h',
         'system/power/power_supply_status.cc',
         'system/power/power_supply_status.h',
         'system/power/tray_power.cc',
         'system/power/tray_power.h',
+        'system/session_length_limit/session_length_limit_observer.h',
+        'system/session_length_limit/tray_session_length_limit.cc',
+        'system/session_length_limit/tray_session_length_limit.h',
         'system/settings/tray_settings.cc',
         'system/settings/tray_settings.h',
         'system/status_area_widget.cc',
         'system/status_area_widget.h',
         'system/status_area_widget_delegate.cc',
         'system/status_area_widget_delegate.h',
         'system/tray/system_tray.cc',
         'system/tray/system_tray.h',
         'system/tray/system_tray_bubble.cc',
         'system/tray/system_tray_bubble.h',
@@ skipping 502 matching lines @@
             'shell/cocoa/app-Info.plist',
           ],
           'xcode_settings': {
             'INFOPLIST_FILE': 'shell/cocoa/app-Info.plist',
           },
         }],
       ],
     },
   ],
 }