Add shutdown notification and service refs to SyncServiceObserver.

components/browsing_data/core/counters/history_counter.h

 // Copyright (c) 2015 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_BROWSING_DATA_CORE_COUNTERS_HISTORY_COUNTER_H_
 #define COMPONENTS_BROWSING_DATA_CORE_COUNTERS_HISTORY_COUNTER_H_
 
 #include <memory>
 
 #include "base/task/cancelable_task_tracker.h"
@@ skipping 40 matching lines @@
  private:
   void Count() override;
 
   void OnGetLocalHistoryCount(history::HistoryCountResult result);
   void OnGetWebHistoryCount(history::WebHistoryService::Request* request,
                             const base::DictionaryValue* result);
   void OnWebHistoryTimeout();
   void MergeResults();
 
   // SyncServiceObserver implementation.
-  void OnStateChanged() override;
+  void OnStateChanged(syncer::SyncService* sync) override;
 
   history::HistoryService* history_service_;
 
   GetUpdatedWebHistoryServiceCallback web_history_service_callback_;
 
   syncer::SyncService* sync_service_;
 
   bool has_synced_visits_;
 
   bool local_counting_finished_;
   bool web_counting_finished_;
 
   base::CancelableTaskTracker cancelable_task_tracker_;
   std::unique_ptr<history::WebHistoryService::Request> web_history_request_;
   base::OneShotTimer web_history_timeout_;
 
   base::ThreadChecker thread_checker_;
 
   BrowsingDataCounter::ResultInt local_result_;
 
   bool history_sync_enabled_;
 
   base::WeakPtrFactory<HistoryCounter> weak_ptr_factory_;
 };
 
 }  // namespace browsing_data
 
 #endif  // COMPONENTS_BROWSING_DATA_CORE_COUNTERS_HISTORY_COUNTER_H_