Add a helper method to create SW SimpleEventCallbacks.

content/browser/service_worker/service_worker_version.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_version.h"
 
 #include <stddef.h>
 
 #include <limits>
 #include <map>
@@ skipping 600 matching lines @@
     external_request_uuid_to_request_id_.erase(iter);
     return FinishRequest(request_id, true, base::Time::Now());
   }
 
   // It is possible that the request was cancelled or timed out before and we
   // won't find it in |external_request_uuid_to_request_id_|.
   // Return true so we don't kill the process.
   return true;
 }
 
+ServiceWorkerVersion::SimpleEventCallback
+ServiceWorkerVersion::CreateSimpleEventCallback(int request_id) {
+  // The weak reference to |this| is safe because storage of the callbacks, the
+  // pending responses of the ServiceWorkerEventDispatcher, is owned by |this|.
+  return base::Bind(&ServiceWorkerVersion::OnSimpleEventFinished,
+                    base::Unretained(this), request_id);
+}
+
 void ServiceWorkerVersion::RunAfterStartWorker(
     ServiceWorkerMetrics::EventType purpose,
     const base::Closure& task,
     const StatusCallback& error_callback) {
   if (running_status() == EmbeddedWorkerStatus::RUNNING) {
     DCHECK(start_callbacks_.empty());
     task.Run();
     return;
   }
   StartWorker(purpose,
@@ skipping 1256 matching lines @@
 
 void ServiceWorkerVersion::CleanUpExternalRequest(
     const std::string& request_uuid,
     ServiceWorkerStatusCode status) {
   if (status == SERVICE_WORKER_OK)
     return;
   external_request_uuid_to_request_id_.erase(request_uuid);
 }
 
 }  // namespace content