Add hook for extension to check sync status.

chrome/browser/sync/profile_sync_service.h

 // 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.
 
 #ifndef CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_H_
 #define CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_H_
 
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 558 matching lines @@
                        const content::NotificationDetails& details) OVERRIDE;
 
   // Changes which data types we're going to be syncing to |preferred_types|.
   // If it is running, the DataTypeManager will be instructed to reconfigure
   // the sync backend so that exactly these datatypes are actively synced.  See
   // class comment for more on what it means for a datatype to be Preferred.
   virtual void ChangePreferredDataTypes(
       syncer::ModelTypeSet preferred_types);
 
   // Returns the set of types which are preferred for enabling. This is a
-  // superset of the active types (see GetActiveTypes()).
+  // superset of the active types (see GetActiveDataTypes()).
   virtual syncer::ModelTypeSet GetPreferredDataTypes() const;
 
   // Gets the set of all data types that could be allowed (the set that
   // should be advertised to the user).  These will typically only change
   // via a command-line option.  See class comment for more on what it means
   // for a datatype to be Registered.
   virtual syncer::ModelTypeSet GetRegisteredDataTypes() const;
 
   // Checks whether the Cryptographer is ready to encrypt and decrypt updates
   // for sensitive data types. Caller must be holding a
@@ skipping 458 matching lines @@
   scoped_ptr<syncer::NetworkResources> network_resources_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileSyncService);
 };
 
 bool ShouldShowActionOnUI(
     const syncer::SyncProtocolError& error);
 
 
 #endif  // CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_H_