Add a helper method to create SW SimpleEventCallbacks.

content/browser/service_worker/service_worker_version_unittest.cc

Index: content/browser/service_worker/service_worker_version_unittest.cc
diff --git a/content/browser/service_worker/service_worker_version_unittest.cc b/content/browser/service_worker/service_worker_version_unittest.cc
index 5639e4da0110dc9b78cf696bed17a09a02fc5222..7558a4c5aae1a5801885636d695407436719bcea 100644
--- a/content/browser/service_worker/service_worker_version_unittest.cc
+++ b/content/browser/service_worker/service_worker_version_unittest.cc
@@ -914,8 +914,8 @@ TEST_F(ServiceWorkerRequestTimeoutTest, RequestTimeout) {
   EXPECT_FALSE(extendable_message_event_callback());
   version_->event_dispatcher()->DispatchExtendableMessageEvent(
       mojom::ExtendableMessageEvent::New(),
-      base::Bind(&ServiceWorkerVersion::OnSimpleEventFinished, version_,
-                 request_id));
+      version_->CreateSimpleEventCallback(request_id));
+
   base::RunLoop().RunUntilIdle();
   // The renderer should have received an ExtendableMessageEvent request.
   EXPECT_TRUE(extendable_message_event_callback());