Add shutdown notification and service refs to SyncServiceObserver.

ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions_bridge.h

Index: ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions_bridge.h
diff --git a/ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions_bridge.h b/ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions_bridge.h
index 9c0eb1d4d1f5c2ec7b1de1161915d7d5ef9ba281..faba31d4da80a5aa298ad6e8894692f1c943d7c5 100644
--- a/ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions_bridge.h
+++ b/ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions_bridge.h
@@ -35,10 +35,10 @@ class SyncedSessionsObserverBridge : public SyncObserverBridge,
                                ios::ChromeBrowserState* browserState);
   ~SyncedSessionsObserverBridge() override;
   // SyncObserverBridge implementation.
-  void OnStateChanged() override;
-  void OnSyncCycleCompleted() override;
-  void OnSyncConfigurationCompleted() override;
-  void OnForeignSessionUpdated() override;
+  void OnStateChanged(syncer::SyncService* sync) override;
+  void OnSyncCycleCompleted(syncer::SyncService* sync) override;
+  void OnSyncConfigurationCompleted(syncer::SyncService* sync) override;
+  void OnForeignSessionUpdated(syncer::SyncService* sync) override;
   // SigninManagerBase::Observer implementation.
   void GoogleSignedOut(const std::string& account_id,
                        const std::string& username) override;