diff -r 000000000000 -r 6474c204b198 xpcom/threads/nsIRunnable.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/threads/nsIRunnable.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 "nsISupports.idl"
+
+/**
+ * Represents a task which can be dispatched to a thread for execution.
+ */
+
+[scriptable, function, uuid(4a2abaf0-6886-11d3-9382-00104ba0fd40)]
+interface nsIRunnable : nsISupports
+{
+    /**
+     * The function implementing the task to be run.
+     */
+    void run();
+};