Add shutdown notification and service refs to SyncServiceObserver.

chrome/browser/history/browsing_history_service.h

 // Copyright 2016 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_HISTORY_BROWSING_HISTORY_SERVICE_H_
 #define CHROME_BROWSER_HISTORY_BROWSING_HISTORY_SERVICE_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 127 matching lines @@
   // Core implementation of history querying.
   void QueryHistory(const base::string16& search_text,
                     const history::QueryOptions& options);
 
   // Removes |items| from history.
   void RemoveVisits(
       std::vector<std::unique_ptr<BrowsingHistoryService::HistoryEntry>>*
           items);
 
   // SyncServiceObserver implementation.
-  void OnStateChanged() override;
+  void OnStateChanged(syncer::SyncService* sync) override;
 
   // Merges duplicate entries from the query results, only retaining the most
   // recent visit to a URL on a particular day. That visit contains the
   // timestamps of the other visits.
   static void MergeDuplicateResults(
       std::vector<BrowsingHistoryService::HistoryEntry>* results);
 
   // Callback from the history system when a history query has completed.
   // Exposed for testing.
   void QueryComplete(const base::string16& search_text,
@@ skipping 93 matching lines @@
 
   // The clock used to vend times.
   std::unique_ptr<base::Clock> clock_;
 
   base::WeakPtrFactory<BrowsingHistoryService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowsingHistoryService);
 };
 
 #endif  // CHROME_BROWSER_HISTORY_BROWSING_HISTORY_SERVICE_H_