diff -r 000000000000 -r 6474c204b198 dom/webidl/PaintRequest.webidl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/webidl/PaintRequest.webidl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,24 @@
+/* -*- 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/. */
+
+/**
+ * These objects are exposed by the MozDOMAfterPaint event. Each one represents
+ * a request to repaint a rectangle that was generated by the browser.
+ */
+interface PaintRequest {
+  /**
+   * The client rect where invalidation was triggered.
+   */
+  readonly attribute DOMRect clientRect;
+
+  /**
+   * The reason for the request, as a string. If an empty string, then we don't know
+   * the reason (this is common). Reasons include "scroll repaint", meaning that we
+   * needed to repaint the rectangle due to scrolling, and "scroll copy", meaning
+   * that we updated the rectangle due to scrolling but instead of painting
+   * manually, we were able to do a copy from another area of the screen.
+   */
+  readonly attribute DOMString reason;
+};