[ServiceWorker] Remove useless ServiceWorkerVersion::DispatchSimpleEvent().

content/common/service_worker/service_worker_event_dispatcher.mojom

Index: content/common/service_worker/service_worker_event_dispatcher.mojom
diff --git a/content/common/service_worker/service_worker_event_dispatcher.mojom b/content/common/service_worker/service_worker_event_dispatcher.mojom
index 5aa62f8717af990ae2739ed397db40dc051f9149..7dd6584ee21cd463eb66c7988ae8a4275c22724b 100644
--- a/content/common/service_worker/service_worker_event_dispatcher.mojom
+++ b/content/common/service_worker/service_worker_event_dispatcher.mojom
@@ -54,6 +54,10 @@ struct ExtendableMessageEvent {
 
 // Renderer-side interface bound to ServiceWorkerContextClient for dispatching
 // events.
+// Those events expecting such response
+// (blink.mojom.ServiceWorkerEventStatus, mojo.common.mojom.Time) are considered
+// 'simple events'. ServiceWorkerVersion::CreateSimpleEventCallback can be used
+// to create the callback for these.
 interface ServiceWorkerEventDispatcher {
   DispatchActivateEvent()
       => (blink.mojom.ServiceWorkerEventStatus status,