Implement updateViaCache flag and no-cache by default for main service worker scripts

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

Index: third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerRegistration.idl
diff --git a/third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerRegistration.idl b/third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerRegistration.idl
index 3c2830659fd2768f277140576726af0d8c206ecd..b34174c82cdfd261bce89ac4d3f009d6af3dc0a2 100644
--- a/third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerRegistration.idl
+++ b/third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerRegistration.idl
@@ -2,6 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+enum ServiceWorkerUpdateViaCache {
+    "imports",
+    "all",
+    "none"
+};
+
 // https://w3c.github.io/ServiceWorker/#service-worker-registration-obj
 [
     ActiveScriptWrappable,
@@ -14,6 +20,7 @@
     [RuntimeEnabled=ServiceWorkerNavigationPreload] readonly attribute NavigationPreloadManager navigationPreload;
 
     readonly attribute USVString scope;
+    readonly attribute ServiceWorkerUpdateViaCache updateViaCache;
 
     [CallWith=ScriptState] Promise<void> update();
     [CallWith=ScriptState] Promise<boolean> unregister();