[extension SW] Support lazy events from extension service workers.

content/public/test/service_worker_test_helpers.h

+// Copyright 2017 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.
+
+#ifndef CONTENT_PUBLIC_TEST_SERVICE_WORKER_TEST_OBSERVER_H_
+#define CONTENT_PUBLIC_TEST_SERVICE_WORKER_TEST_OBSERVER_H_
+
+#include "base/callback_forward.h"
+
+class GURL;
+namespace content {
+
+class ServiceWorkerContext;
+
+// Stops a running service worker registered for |pattern|, and calls

[falken, 2017/06/23 03:45:46]

This is underspecified, there could be multiple workers running for pattern.

"Stops the active service worker of the registration whose scope is |pattern|."

[lazyboy, 2017/06/23 07:44:56]

Done.

+// |complete_callback_ui| callback on UI thread when done.
+//
+// Can be called from UI/IO thread.
+void StopServiceWorkerForPattern(ServiceWorkerContext* context,
+                                 const GURL& pattern,
+                                 base::OnceClosure complete_callback_ui);
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_TEST_SERVICE_WORKER_TEST_OBSERVER_H_