Implement the events for Background Fetch

third_party/WebKit/Source/modules/background_fetch/BackgroundFetchClickEvent.idl

Index: third_party/WebKit/Source/modules/background_fetch/BackgroundFetchClickEvent.idl
diff --git a/third_party/WebKit/Source/modules/background_fetch/BackgroundFetchClickEvent.idl b/third_party/WebKit/Source/modules/background_fetch/BackgroundFetchClickEvent.idl
new file mode 100644
index 0000000000000000000000000000000000000000..08591605e3f2d4cf85a084ab17ffb363d7ee72a7
--- /dev/null
+++ b/third_party/WebKit/Source/modules/background_fetch/BackgroundFetchClickEvent.idl
@@ -0,0 +1,15 @@
+// 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.
+
+// https://wicg.github.io/background-fetch/#background-fetch-click-event
+
+enum BackgroundFetchState { "pending", "succeeded", "failed" };
+
+[
+    Constructor(DOMString type, BackgroundFetchClickEventInit init),
+    Exposed=ServiceWorker,
+    RuntimeEnabled=BackgroundFetch
+] interface BackgroundFetchClickEvent : BackgroundFetchEvent {
+    readonly attribute BackgroundFetchState state;
+};