NotificationController::clientFrom() should return a reference

Source/modules/notifications/NotificationController.h

Index: Source/modules/notifications/NotificationController.h
diff --git a/Source/modules/notifications/NotificationController.h b/Source/modules/notifications/NotificationController.h
index d2dee1cc2db7e1b8b3094809b005bcf4feed2213..52e22bf90536002ba78d17ab187c6005358a265d 100644
--- a/Source/modules/notifications/NotificationController.h
+++ b/Source/modules/notifications/NotificationController.h
@@ -42,15 +42,15 @@ public:
     static PassOwnPtr<NotificationController> create(PassOwnPtr<NotificationClient>);
     static const char* supplementName();
     static NotificationController* from(LocalFrame* frame) { return static_cast<NotificationController*>(Supplement<LocalFrame>::from(frame, supplementName())); }
-    static NotificationClient* clientFrom(LocalFrame*);
-
-    NotificationClient* client() { return m_client.get(); }
+    static NotificationClient& clientFrom(LocalFrame*);
 
     virtual void trace(Visitor* visitor) OVERRIDE { Supplement<LocalFrame>::trace(visitor); }
 
 private:
     explicit NotificationController(PassOwnPtr<NotificationClient>);
 
+    NotificationClient& client() { return *m_client; }
+
     OwnPtr<NotificationClient> m_client;
 };