[Background Sync] Converting Blink code to the MVP API

Source/modules/background_sync/PeriodicSyncRegistration.idl

Index: Source/modules/background_sync/PeriodicSyncRegistration.idl
diff --git a/Source/modules/background_sync/PeriodicSyncRegistration.idl b/Source/modules/background_sync/PeriodicSyncRegistration.idl
new file mode 100644
index 0000000000000000000000000000000000000000..4cc19f630dd78a048d7d0d2dd18b015c117c88de
--- /dev/null
+++ b/Source/modules/background_sync/PeriodicSyncRegistration.idl
@@ -0,0 +1,26 @@
+// 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 SyncNetworkState {
+  "any",
+  "avoid-cellular",
+  "online"
+};
+
+enum SyncPowerState {
+  "auto",
+  "avoid-draining"
+};
+
+[
+    Exposed=(Window,ServiceWorker),
+    GarbageCollected,
+    RuntimeEnabled=BackgroundSync,
+] interface PeriodicSyncRegistration {
+    [RuntimeEnabled=BackgroundSyncV2] readonly attribute DOMString tag;
+    [RuntimeEnabled=BackgroundSyncV2] readonly attribute unsigned long minPeriod;
+    [RuntimeEnabled=BackgroundSyncV2] readonly attribute SyncNetworkState networkState;
+    [RuntimeEnabled=BackgroundSyncV2] readonly attribute SyncPowerState powerState;
+    [CallWith=ScriptState] Promise<boolean> unregister();
+};