Add the first app_shell_browsertest test.

extensions/test/data/platform_app/world.js

Index: extensions/test/data/platform_app/world.js
diff --git a/chrome/test/data/extensions/platform_apps/ephemeral_apps/messaging_receiver/index.js b/extensions/test/data/platform_app/world.js
similarity index 64%
copy from chrome/test/data/extensions/platform_apps/ephemeral_apps/messaging_receiver/index.js
copy to extensions/test/data/platform_app/world.js
index dc590d190815d0645476120ece798c9fb5b4db35..5338f1ff5af21e482d2efecff9e154b7ab5ef905 100644
--- a/chrome/test/data/extensions/platform_apps/ephemeral_apps/messaging_receiver/index.js
+++ b/extensions/test/data/platform_app/world.js
@@ -1,7 +1,7 @@
 // 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.
-
-onload = function() {
-  chrome.test.sendMessage('launched');
+window.onload = function() {

[James Cook, 2014/04/08 16:03:49]

nit: blank line above

[Yoyo Zhou, 2014/04/08 21:55:21]

Done.

P.S. I log here because it's how I know the test is actually working.

+  console.log('app window opened');
+  chrome.test.notifyPass();
 };