[Background Sync] Converting Blink code to the MVP API

Source/modules/background_sync/SyncRegistrationOptions.idl

 // Copyright 2015 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.
 
-enum SyncNetworkType {
-  "network-any",
-  "network-offline",
-  "network-online",
-  "network-non-mobile",
+[
+    RuntimeEnabled=BackgroundSyncV2,
+] dictionary SyncRegistrationOptions {
+    DOMString tag;
 };
-
-[
-    RuntimeEnabled=BackgroundSync,
-] dictionary SyncRegistrationOptions {
-    DOMString id;
-    unsigned long minDelay = 0;
-    unsigned long maxDelay = 0;
-    unsigned long minPeriod = 0;
-    SyncNetworkType minRequiredNetwork = "network-online";
-    boolean allowOnBattery = true;
-    boolean idleRequired = false;
-};