diff -r 000000000000 -r 6474c204b198 dom/interfaces/settings/nsISettingsService.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/interfaces/settings/nsISettingsService.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,36 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "domstubs.idl"
+
+[scriptable, uuid(aad47850-2e87-11e2-81c1-0800200c9a66)]
+interface nsISettingsServiceCallback : nsISupports
+{
+  void handle(in DOMString aName, in jsval aResult);
+  void handleError(in DOMString aErrorMessage);
+};
+
+[scriptable, uuid(f1b3d820-8e75-11e3-baa8-0800200c9a66)]
+interface nsISettingsTransactionCompleteCallback : nsISupports
+{
+  void handle();
+  void handleAbort(in DOMString aErrorMessage);
+};
+
+[scriptable, uuid(d7a395a0-e292-11e1-834e-1761d57f5f99)]
+interface nsISettingsServiceLock : nsISupports
+{
+  void set(in string aName,
+           in jsval aValue,
+           in nsISettingsServiceCallback aCallback,
+           [optional] in string aMessage);
+
+  void get(in string aName, in nsISettingsServiceCallback aCallback);
+};
+
+[scriptable, uuid(0505acf0-8e76-11e3-baa8-0800200c9a66)]
+interface nsISettingsService : nsISupports
+{
+  nsISettingsServiceLock createLock([optional] in nsISettingsTransactionCompleteCallback aCallback);
+};