Inform the client when the Service Worker rejects an install event

public/platform/WebServiceWorkerEventResult.h

+// Copyright 2014 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 WebServiceWorkerEventResult_h
+#define WebServiceWorkerEventResult_h
+
+namespace blink {
+
+// Indicates how the service worker handled an event.
+enum WebServiceWorkerEventResult {
+    // The event dispatch completed with no rejections.
+    WebServiceWorkerEventResultCompleted = 0,
+    // The service worker associated the event with a promise that was rejected
+    // (e.g., the promise passed to waitUntil for an install event was rejected).
+    WebServiceWorkerEventResultRejected,
+    WebServiceWorkerEventResultLast = WebServiceWorkerEventResultRejected
+};
+
+} // namespace blink
+
+#endif // WebServiceWorkerEventResult_h