sync: Move migration signal out of snapshot

sync/sessions/status_controller.h

 // 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.
 
 // StatusController handles all counter and status related number crunching and
 // state tracking on behalf of a SyncSession.
 //
 // This object may be accessed from many different threads.  It will be accessed
 // most often from the syncer thread.  However, when update application is in
 // progress it may also be accessed from the worker threads.  This is safe
@@ skipping 78 matching lines @@
   // Commit counters.
   void increment_num_successful_commits();
   void increment_num_successful_bookmark_commits();
   void set_num_successful_bookmark_commits(int value);
 
   // Server communication status tracking.
   void set_last_get_key_result(const SyncerError result);
   void set_last_download_updates_result(const SyncerError result);
   void set_commit_result(const SyncerError result);
 
-  // A very important flag used to inform frontend of need to migrate.
-  void set_types_needing_local_migration(ModelTypeSet types);
-
   void UpdateStartTime();
 
  private:
   ModelNeutralState model_neutral_;
 
   base::Time sync_start_time_;
 
   DISALLOW_COPY_AND_ASSIGN(StatusController);
 };
 
 }  // namespace sessions
 }  // namespace syncer
 
 #endif  // SYNC_SESSIONS_STATUS_CONTROLLER_H_