Implement support for <extensionoptions> embedding in WebUI

chrome/test/data/extensions/webui/can_embed_extension_options.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// out/Debug/browser_tests --gtest_filter=ExtensionWebUITest.SendMessage
-
+// out/Debug/browser_tests
+//     --gtest_filter=ExtensionWebUITest.CanEmbedExtensionOptions
 if (!chrome || !chrome.test || !chrome.test.sendMessage) {
   console.error('chrome.test.sendMessage is unavailable on ' +
                 document.location.href);
   domAutomationController.send(false);
   return;
 }
 
-chrome.test.sendMessage('ping', function(reply) {
-  if (reply != 'pong') {
-    console.error('Expected "pong", Actual ' + JSON.stringify(reply));
-    chrome.test.sendMessage('false');
-  } else {
-    chrome.test.sendMessage('true');
-  }
+var extensionoptions = document.createElement('extensionoptions');

[not at google - send to devlin, 2014/08/07 23:06:03]

I remember we moved this out of here as a speculative fix, but it's probably
better inside the function scope if possible.

[ericzeng, 2014/08/08 00:23:47]

Done.

+chrome.test.sendMessage('ready', function(reply) {
+
+  extensionoptions.addEventListener('load', function() {
+    chrome.test.sendMessage('guest loaded');
+  });
+  extensionoptions.setAttribute('extension', reply);
+  document.body.appendChild(extensionoptions);
+
 });
 
 domAutomationController.send(true);