Add shutdown notification and service refs to SyncServiceObserver.

chrome/browser/history/browsing_history_service.cc

Index: chrome/browser/history/browsing_history_service.cc
diff --git a/chrome/browser/history/browsing_history_service.cc b/chrome/browser/history/browsing_history_service.cc
index a02601a60e744214f4962fd282d500832cc79a29..ccc285f33a6b171bb7aa218e4a641c136292a35d 100644
--- a/chrome/browser/history/browsing_history_service.cc
+++ b/chrome/browser/history/browsing_history_service.cc
@@ -152,7 +152,7 @@ BrowsingHistoryService::~BrowsingHistoryService() {
   web_history_request_.reset();
 }
 
-void BrowsingHistoryService::OnStateChanged() {
+void BrowsingHistoryService::OnStateChanged(syncer::SyncService* sync) {
   // If the history sync was enabled, start observing WebHistoryService.
   // This method should not be called after we already added the observer.
   history::WebHistoryService* web_history =