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

content/common/service_worker/service_worker_event_dispatcher.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module content.mojom;
 
 import "components/payments/content/payment_app.mojom";
 import "content/common/url_loader.mojom";
 import "mojo/common/string16.mojom";
 import "mojo/common/time.mojom";
@@ skipping 36 matching lines @@
 
 struct ExtendableMessageEvent {
   mojo.common.mojom.String16 message;
   url.mojom.Origin source_origin;
   array<handle<message_pipe>> message_ports;
   ExtendableMessageEventSource source;
 };
 
 // Renderer-side interface bound to ServiceWorkerContextClient for dispatching
 // events.
+// Those events expecting such response
+// (blink.mojom.ServiceWorkerEventStatus, mojo.common.mojom.Time) are dispatched
+// as 'simple event'. See ServiceWorkerVersion for implementation details.

[falken, 2017/03/30 08:21:29]

I would rather phrase this as "... are considered 'simple events'.
ServiceWorkerVersion::CreateSimpleEventCallback can be used to create the
callback for these".

Otherwise it sounds like there is a material difference between how to dispatch
a simple event and non-simple event.

[leonhsl(Using Gerrit), 2017/03/30 09:46:34]

Done.

 interface ServiceWorkerEventDispatcher {
   DispatchActivateEvent()
       => (blink.mojom.ServiceWorkerEventStatus status,
           mojo.common.mojom.Time dispatch_event_time);
   DispatchBackgroundFetchAbortEvent(string tag)
       => (blink.mojom.ServiceWorkerEventStatus status,
           mojo.common.mojom.Time dispatch_event_time);
   DispatchBackgroundFetchClickEvent(string tag, BackgroundFetchState state)
       => (blink.mojom.ServiceWorkerEventStatus status,
           mojo.common.mojom.Time dispatch_event_time);
@@ skipping 36 matching lines @@
   DispatchExtendableMessageEvent(ExtendableMessageEvent event)
       => (blink.mojom.ServiceWorkerEventStatus status,
           mojo.common.mojom.Time dispatch_event_time);
 
   // Pings the service worker to check if it is responsive. If the callback is
   // not called within a certain period of time, the browser will terminate the
   // worker. Unlike the other functions in this interface, Ping() does not
   // dispatch an event.
   Ping() => ();
 };