Enable <adview> tag for packaged apps.

chrome/test/data/extensions/platform_apps/ad_view/ad_network_loaded/chrometest.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.
+
+chrome.test.getConfig(function(config) {
+  var guestURL = 'http://localhost:' + config.testServer.port +
+      '/files/extensions/platform_apps/ad_view/ad_network/testsdk.html';
+
+  var adview = document.getElementsByTagName("adview")[0];
+
+  adview.addEventListener("loadcommit", function() {
+    adview.contentWindow.postMessage({
+      message: "onloadcommit",
+      data: "data"
+    }, "*");
+  })
+
+  adview.setAttribute("src", guestURL);
+
+  window.addEventListener("message", function(event) {
+    if (event.data.message == "onloadcommit-ack") {
+      chrome.test.sendMessage("ad-network-loaded");
+    }
+  })
+});