diff -r 000000000000 -r 6474c204b198 dom/browser-element/mochitest/browserElement_XFrameOptionsDeny.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/browser-element/mochitest/browserElement_XFrameOptionsDeny.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,79 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 770239 - Test that X-Frame-Options will correctly block a page inside a
+// subframe of <iframe mozbrowser>.
+"use strict";
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+var initialScreenshotArrayBuffer;
+
+function arrayBuffersEqual(a, b) {
+  var x = new Int8Array(a);
+  var y = new Int8Array(b);
+  if (x.length != y.length) {
+    return false;
+  }
+
+  for (var i = 0; i < x.length; i++) {
+    if (x[i] != y[i]) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+function runTest() {
+  var iframe = document.createElement('iframe');
+  SpecialPowers.wrap(iframe).mozbrowser = true;
+
+  // Our child will create two iframes, so make sure this iframe is big enough
+  // to show both of them without scrolling, so taking a screenshot gets both
+  // frames.
+  iframe.height = '1000px';
+
+  iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
+    switch (e.detail.message) {
+    case 'step 1':
+      // Make the page wait for us to unblock it (which we do after we finish
+      // taking the screenshot).
+      e.preventDefault();
+
+      iframe.getScreenshot(1000, 1000).onsuccess = function(sshot) {
+        var fr = new FileReader();
+        fr.onloadend = function() {
+          initialScreenshotArrayBuffer = fr.result;
+          e.detail.unblock();
+        }
+        fr.readAsArrayBuffer(sshot.target.result);
+      };
+      break;
+    case 'step 2':
+      // The page has now attempted to load the X-Frame-Options page; take
+      // another screenshot.
+      iframe.getScreenshot(1000, 1000).onsuccess = function(sshot) {
+        var fr = new FileReader();
+        fr.onloadend = function() {
+          ok(arrayBuffersEqual(fr.result, initialScreenshotArrayBuffer),
+             "Screenshots should be identical");
+          SimpleTest.finish();
+        }
+        fr.readAsArrayBuffer(sshot.target.result);
+      };
+      break;
+    }
+  });
+
+  document.body.appendChild(iframe);
+
+  // Load this page from a different origin than ourselves.  This page will, in
+  // turn, load a child from mochi.test:8888, our origin, with X-Frame-Options:
+  // SAMEORIGIN.  That load should be denied.
+  iframe.src = 'http://example.com/tests/dom/browser-element/mochitest/file_browserElement_XFrameOptionsDeny.html';
+}
+
+addEventListener('testready', runTest);