Expose Durable Storage API to script

Source/modules/quota/StorageManager.idl

Index: Source/modules/quota/StorageManager.idl
diff --git a/Source/modules/quota/StorageManager.idl b/Source/modules/quota/StorageManager.idl
new file mode 100644
index 0000000000000000000000000000000000000000..31038b6f02e8ca1fc2b3de778fc5e1004e6f9f4e
--- /dev/null
+++ b/Source/modules/quota/StorageManager.idl
@@ -0,0 +1,15 @@
+// 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 PersistentStoragePermission { "default", "denied", "granted" };
+
+[
+    Exposed=(Window,Worker),
+    TypeChecking=Interface,
+    GarbageCollected,
+    RuntimeEnabled=DurableStorage,
+] interface StorageManager {
+    [CallWith=ScriptState] Promise<PersistentStoragePermission> requestPersistent();
+    Promise<PersistentStoragePermission> persistentPermission();
+};