diff -r 000000000000 -r 6474c204b198 layout/generic/nsIScrollPositionListener.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/generic/nsIScrollPositionListener.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,23 @@
+/* -*- 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/. */
+
+#ifndef nsIScrollPositionListener_h___
+#define nsIScrollPositionListener_h___
+
+#include "nsCoord.h"
+
+/**
+ * Provides a way to learn about scroll position changes of nsIScrollableFrame's.
+ */
+class nsIScrollPositionListener {
+public:
+
+	virtual void ScrollPositionWillChange(nscoord aX, nscoord aY) = 0;
+	virtual void ScrollPositionDidChange(nscoord aX, nscoord aY) = 0;
+};
+
+#endif /* nsIScrollPositionListener_h___ */
+