[sync] Isolate FOREIGN_SESSION_UPDATED notification in ProfileSyncService

components/sync_driver/sync_service_observer.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 COMPONENTS_SYNC_DRIVER_SYNC_SERVICE_OBSERVER_H_
 #define COMPONENTS_SYNC_DRIVER_SYNC_SERVICE_OBSERVER_H_
 
 namespace sync_driver {
 
 // Various UI components such as the New Tab page can be driven by observing
@@ skipping 12 matching lines @@
   virtual void OnStateChanged() = 0;
 
   // If a client wishes to handle sync cycle completed events in a special way,
   // they can use this function.  By default, it re-routes to OnStateChanged().
   virtual void OnSyncCycleCompleted();
 
   // Called when the sync service has finished the datatype configuration
   // process.
   virtual void OnSyncConfigurationCompleted() {}
 
+  // Called when a foreign session has been updated.
+  virtual void OnForeignSessionUpdated() {}
+
  protected:
   virtual ~SyncServiceObserver() {}
 };
 
 }  // namespace sync_driver
 
 #endif  // COMPONENTS_SYNC_DRIVER_SYNC_SERVICE_OBSERVER_H_