Refactor preference syncing.

content/common/notification_type.h

 // Copyright (c) 2011 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.
 
 #ifndef CONTENT_COMMON_NOTIFICATION_TYPE_H_
 #define CONTENT_COMMON_NOTIFICATION_TYPE_H_
 #pragma once
 
 // This file describes various types used to describe and filter notifications
 // that pass through the NotificationService.
@@ skipping 1100 matching lines @@
     // Sent when the geolocation settings change. The source is the
     // GeolocationContentSettingsMap object, the details are
     // ContentSettingsNotificationsDetails.
     GEOLOCATION_SETTINGS_CHANGED,
 
     // Sync --------------------------------------------------------------------
 
     // Sent when the syncer is blocked configuring.
     SYNC_CONFIGURE_BLOCKED,
 
+    // The ProfileSyncService is loading. Components can now call
+    // Profile::GetProfileSyncService without risk of premature creation.
+    // This notification occurs only after the PSS has begun initialization.
+    PROFILE_SYNC_SERVICE_LOADING,
+
     // The sync service has started the configuration process.
     SYNC_CONFIGURE_START,
 
     // The sync service is finished the configuration process.
     SYNC_CONFIGURE_DONE,
 
     // The session service has been saved.  This notification type is only sent
     // if there were new SessionService commands to save, and not for no-op save
     // operations.
     SESSION_SERVICE_SAVED,
@@ skipping 209 matching lines @@
 };
 
 inline bool operator==(NotificationType::Type a, NotificationType b) {
   return a == b.value;
 }
 inline bool operator!=(NotificationType::Type a, NotificationType b) {
   return a != b.value;
 }
 
 #endif  // CONTENT_COMMON_NOTIFICATION_TYPE_H_