Factor Google Now welcome notifications out of DesktopNotificationService.

chrome/chrome_browser.gypi

 # Copyright 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': {
     # All .cc, .h, .m, and .mm files under browser except for:
     # * tests and mocks.
     # * code below browser/chromeos
     # * code below browser/extensions
@@ skipping 1733 matching lines @@
     # Used on all platforms when notifications are enabled.
     'chrome_browser_notifications_sources': [
       'browser/notifications/desktop_notification_infobar_delegate.cc',
       'browser/notifications/desktop_notification_infobar_delegate.h',
       'browser/notifications/desktop_notification_profile_util.cc',
       'browser/notifications/desktop_notification_profile_util.h',
       'browser/notifications/desktop_notification_service.cc',
       'browser/notifications/desktop_notification_service.h',
       'browser/notifications/desktop_notification_service_factory.cc',
       'browser/notifications/desktop_notification_service_factory.h',
-      'browser/notifications/extension_welcome_notification.cc',
-      'browser/notifications/extension_welcome_notification.h',
-      'browser/notifications/google_now_notification_stats_collector.cc',
-      'browser/notifications/google_now_notification_stats_collector.h',
       'browser/notifications/message_center_notification_manager_win.cc',
       'browser/notifications/notification.cc',
       'browser/notifications/notification.h',
       'browser/notifications/screen_lock_notification_blocker.cc',
       'browser/notifications/screen_lock_notification_blocker.h',
       'browser/notifications/fullscreen_notification_blocker.cc',
       'browser/notifications/fullscreen_notification_blocker.h',
       'browser/notifications/login_state_notification_blocker_chromeos.cc',
       'browser/notifications/login_state_notification_blocker_chromeos.h',
       'browser/notifications/notification_delegate.cc',
       'browser/notifications/notification_delegate.h',
       'browser/notifications/notification_object_proxy.cc',
       'browser/notifications/notification_object_proxy.h',
       'browser/notifications/notification_system_observer.cc',
       'browser/notifications/notification_system_observer.h',
       'browser/notifications/notification_ui_manager.h',
       'browser/notifications/notification_ui_manager_android.cc',
       'browser/notifications/notification_ui_manager_android.h',
     ],
     # Used on non-Android platforms when notifications are enabled.
     'chrome_browser_non_android_notifications_sources': [
+      'browser/notifications/extensions/extension_welcome_notification.cc',
+      'browser/notifications/extensions/extension_welcome_notification.h',
+      'browser/notifications/extensions/extension_welcome_notification_factory.cc',
+      'browser/notifications/extensions/extension_welcome_notification_factory.h',
+      'browser/notifications/extensions/google_now_notification_stats_collector.cc',
+      'browser/notifications/extensions/google_now_notification_stats_collector.h',
       'browser/notifications/message_center_notification_manager.cc',
       'browser/notifications/message_center_notification_manager.h',
       'browser/notifications/message_center_settings_controller.cc',
       'browser/notifications/message_center_settings_controller.h',
       'browser/notifications/message_center_stats_collector.cc',
       'browser/notifications/message_center_stats_collector.h',
       'browser/notifications/notification_conversion_helper.h',
       'browser/notifications/notification_conversion_helper.cc',
       'browser/notifications/notification_ui_manager_desktop.cc',
       'browser/notifications/sync_notifier/chrome_notifier_service.cc',
@@ skipping 1762 matching lines @@
           'variables': {
             'proto_in_dir': 'browser/sync_file_system/drive_backend',
             'proto_out_dir': 'chrome/browser/sync_file_system/drive_backend',
           },
           'includes': [ '../build/protoc.gypi' ]
         },
       ],
     },],
   ],
 }