Add IPC messages for ARC notification

components/arc/arc_bridge_service.cc

Index: components/arc/arc_bridge_service.cc
diff --git a/components/arc/arc_bridge_service.cc b/components/arc/arc_bridge_service.cc
index 640e3792fb909c8e4c264acf9f06c971aad675e7..39072fd71c834083bfb9f18fb5995ac8df04a350 100644
--- a/components/arc/arc_bridge_service.cc
+++ b/components/arc/arc_bridge_service.cc
@@ -57,6 +57,17 @@ void ArcBridgeService::RemoveObserver(Observer* observer) {
   observer_list_.RemoveObserver(observer);
 }
 
+void ArcBridgeService::AddNotificationObserver(NotificationObserver* observer) {
+  DCHECK(origin_task_runner()->RunsTasksOnCurrentThread());
+  notification_observer_list_.AddObserver(observer);
+}
+
+void ArcBridgeService::RemoveNotificationObserver(
+    NotificationObserver* observer) {
+  DCHECK(origin_task_runner()->RunsTasksOnCurrentThread());
+  notification_observer_list_.RemoveObserver(observer);
+}
+
 void ArcBridgeService::AddAppObserver(AppObserver* observer) {
   DCHECK(origin_task_runner()->RunsTasksOnCurrentThread());
   app_observer_list_.AddObserver(observer);