Implement initial chrome.browserAction.openPopup API.

chrome/test/data/extensions/api_test/browser_action/open_popup/open_popup_fails.js

+// Copyright (c) 2013 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.
+
+// Notify pass to return control to the ApiTest. This needs to be done in 2
+// passes so we can open the popup from the ApiTest side because loading an
+// extension hides any open popups. After a popup is opened, we can assert that
+// a popup fails to open with this API.
+chrome.test.notifyPass();
+chrome.test.sendMessage('ready', function() {
+  chrome.browserAction.openPopup(function(popupWindow2) {
+    // This popup should fail to open.
+    chrome.test.assertTrue(!popupWindow2);
+    chrome.test.succeed();
+  });
+});