From 8c0762a32a24666dbcfdc4115c1e927ef02f8a11 Mon Sep 17 00:00:00 2001
From: Yury Delendik <ydelendik@mozilla.com>
Date: Fri, 11 Apr 2014 12:10:42 -0500
Subject: [PATCH] Adds then method to the RenderTask

---
 src/display/api.js | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/display/api.js b/src/display/api.js
index 7495907e1..7185cbbbf 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -1185,6 +1185,18 @@ var RenderTask = (function RenderTaskClosure() {
     cancel: function RenderTask_cancel() {
       this.internalRenderTask.cancel();
       this.promise.reject(new Error('Rendering is cancelled'));
+    },
+
+    /**
+     * Registers callback to indicate the rendering task completion.
+     *
+     * @param {function} onFulfilled The callback for the rendering completion.
+     * @param {function} onRejected The callback for the rendering failure.
+     * @return {Promise} A promise that is resolved after the onFulfilled or
+     *                   onRejected callback.
+     */
+    then: function RenderTask_then(onFulfilled, onRejected) {
+      return this.promise.then(onFulfilled, onRejected);
     }
   };