Remove most remaining sync/notifier dependencies

sync/sessions/nudge_tracker.h

 // Copyright 2013 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.
 //
 // A class to track the outstanding work required to bring the client back into
 // sync with the server.
 #ifndef SYNC_SESSIONS_NUDGE_TRACKER_H_
 #define SYNC_SESSIONS_NUDGE_TRACKER_H_
 
 #include <list>
 #include <map>
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "sync/base/sync_export.h"
+#include "sync/internal_api/public/base/invalidation_interface.h"
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/protocol/sync.pb.h"
 #include "sync/sessions/data_type_tracker.h"
 
 namespace syncer {
 
 class ObjectIdInvalidationMap;
 
 namespace sessions {
 
@@ skipping 156 matching lines @@
   // currently in a sync cycle.
   base::TimeTicks sync_cycle_start_time_;
 
   DISALLOW_COPY_AND_ASSIGN(NudgeTracker);
 };
 
 }  // namespace sessions
 }  // namespace syncer
 
 #endif  // SYNC_SESSIONS_NUDGE_TRACKER_H_