Start implementing ForeignFetchEvent for foreign fetch events.

third_party/WebKit/Source/modules/serviceworkers/ForeignFetchEvent.idl

Index: third_party/WebKit/Source/modules/serviceworkers/ForeignFetchEvent.idl
diff --git a/third_party/WebKit/Source/modules/serviceworkers/FetchEvent.idl b/third_party/WebKit/Source/modules/serviceworkers/ForeignFetchEvent.idl
similarity index 60%
copy from third_party/WebKit/Source/modules/serviceworkers/FetchEvent.idl
copy to third_party/WebKit/Source/modules/serviceworkers/ForeignFetchEvent.idl
index e8f4551dcbe0d43b6f28ab6ecae7cd06f0253697..c3a256d77e75a56fb4c7d869b8a18cbca8bbffa2 100644
--- a/third_party/WebKit/Source/modules/serviceworkers/FetchEvent.idl
+++ b/third_party/WebKit/Source/modules/serviceworkers/ForeignFetchEvent.idl
@@ -2,14 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// https://slightlyoff.github.io/ServiceWorker/spec/service_worker/index.html#fetch-event-interface
+// https://slightlyoff.github.io/ServiceWorker/spec/service_worker/index.html#foreign-fetch-event-section
 [
-    Constructor(DOMString type, FetchEventInit eventInitDict),
+    Constructor(DOMString type, ForeignFetchEventInit eventInitDict),
     Exposed=ServiceWorker,
-] interface FetchEvent : ExtendableEvent {
+    RuntimeEnabled=ForeignFetch,
+] interface ForeignFetchEvent : ExtendableEvent {
     [SameObject] readonly attribute Request request;
-    readonly attribute DOMString? clientId;
-    readonly attribute boolean isReload;
 
-    [CallWith=ScriptState, RaisesException] void respondWith(Promise<Response> r);
+    [CallWith=ScriptState, RaisesException] void respondWith(Promise<ForeignFetchResponse> r);
 };