diff -r 000000000000 -r 6474c204b198 dom/system/gonk/nsIVolumeStat.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/system/gonk/nsIVolumeStat.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+/* 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"
+
+[scriptable, uuid(b4c050d0-c57a-11e1-9b21-0800200c9a66)]
+interface nsIVolumeStat : nsISupports
+{
+    readonly attribute  long long   totalBytes;
+    readonly attribute  long long   freeBytes;
+};