Mojoify FetchEvent of Service Worker.

content/browser/service_worker/service_worker_version.h

Index: content/browser/service_worker/service_worker_version.h
diff --git a/content/browser/service_worker/service_worker_version.h b/content/browser/service_worker/service_worker_version.h
index 5026700bcbe09f5a78f3a83a27c1700d9fe29a70..e30b02f0668d31a89734425231d9b4391cbaf074 100644
--- a/content/browser/service_worker/service_worker_version.h
+++ b/content/browser/service_worker/service_worker_version.h
@@ -369,6 +369,10 @@ class CONTENT_EXPORT ServiceWorkerVersion
   // requests, in-progress streaming URLRequestJobs, or pending start callbacks.
   bool HasWork() const;
 
+  base::WeakPtr<ServiceWorkerVersion> GetWeakPtr() {
+    return weak_factory_.GetWeakPtr();
+  }
+
  private:
   friend class base::RefCounted<ServiceWorkerVersion>;
   friend class ServiceWorkerMetrics;