Add a helper method to create SW SimpleEventCallbacks.

content/browser/service_worker/service_worker_dispatcher_host.cc

 // Copyright 2013 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.
 
 #include "content/browser/service_worker/service_worker_dispatcher_host.h"
 
 #include <utility>
 
 #include "base/debug/crash_logging.h"
 #include "base/logging.h"
@@ skipping 1222 matching lines @@
   event->source = source;
 
   // Hide the client url if the client has a unique origin.
   if (source_origin.unique()) {
     if (event->source.client_info.IsValid())
       event->source.client_info.url = GURL();
     else
       event->source.service_worker_info.url = GURL();
   }
 
-  // |event_dispatcher| is owned by |worker|, once |worker| got destroyed, the
-  // bound function will never be called, so it is safe to use
-  // base::Unretained() here.
   worker->event_dispatcher()->DispatchExtendableMessageEvent(
-      std::move(event), base::Bind(&ServiceWorkerVersion::OnSimpleEventFinished,
-                                   base::Unretained(worker.get()), request_id));
+      std::move(event), worker->CreateSimpleEventCallback(request_id));
 }
 
 template <typename SourceInfo>
 void ServiceWorkerDispatcherHost::DidFailToDispatchExtendableMessageEvent(
     const std::vector<int>& sent_message_ports,
     const SourceInfo& source_info,
     const StatusCallback& callback,
     ServiceWorkerStatusCode status) {
   // Transfering the message ports failed, so destroy the ports.
   for (int port : sent_message_ports)
@@ skipping 547 matching lines @@
   if (!handle) {
     bad_message::ReceivedBadMessage(this,
                                     bad_message::SWDH_TERMINATE_BAD_HANDLE);
     return;
   }
   handle->version()->StopWorker(
       base::Bind(&ServiceWorkerUtils::NoOpStatusCallback));
 }
 
 }  // namespace content