diff -r 000000000000 -r 6474c204b198 dom/interfaces/base/nsIIdleObserver.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/interfaces/base/nsIIdleObserver.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,16 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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(37916e05-e062-4f72-96d5-660cfb55e9b6)]
+interface nsIIdleObserver : nsISupports
+{
+  // Time is in seconds and is read only when idle observers are added
+  // and removed.
+  readonly attribute unsigned long time;
+  void onidle();
+  void onactive();
+};