Minor cleanup in web_view_browsertest and remove repetitive code.

chrome/test/data/extensions/platform_apps/web_view/download/embedder.js

 // Copyright 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.
 
 var embedder = {};
 embedder.baseGuestURL = '';
 embedder.guestURL = '';
 
 /** @private */
 embedder.setUpGuest_ = function() {
@@ skipping 12 matching lines @@
       var url = e.url;
       if (url.indexOf('expect-deny.zip') != -1) {
         e.request.deny();
       } else if (url.indexOf('expect-allow.zip') != -1) {
         e.request.allow();
       } else {
         // Ignore.
       }
     }
   });
+  var loaded = false;
+  webview.addEventListener('loadstop', function(e) {
+    if (!loaded) {
+      loaded = true;
+      chrome.test.sendMessage('guest-loaded');
+    }
+  });
   return webview;
 };
 
 onload = function() {
   chrome.test.getConfig(function(config) {
     embedder.baseGuestURL = 'http://localhost:' + config.testServer.port;
     embedder.guestURL = embedder.baseGuestURL +
         '/files/extensions/platform_apps/web_view/download/guest.html';
     embedder.setUpGuest_();
   });
 };