<webview>: Make contentWindow available prior to attachment (on display:none).

chrome/test/data/extensions/platform_apps/web_view/shim/main.js

 // Copyright (c) 2012 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 util = {};
 var embedder = {};
 embedder.baseGuestURL = '';
 embedder.emptyGuestURL = '';
 embedder.windowOpenGuestURL = '';
 embedder.noReferrerGuestURL = '';
@@ skipping 1720 matching lines @@
       return;
     }
     window.console.log('Unexpected message: \'' + data[0]  + '\'');
     embedder.test.fail();
   });
   document.body.appendChild(webview);
 }
 
 function testPostMessageCommChannel() {
   var webview = new WebView();
+  // Run this test with display:none to verify that postMessage works correctly.
+  webview.style.display = 'none';
   webview.src = 'about:blank';
   webview.addEventListener('loadstop', function(e) {
+    window.console.log('loadstop');
     webview.executeScript(
       {file: 'inject_comm_channel.js'},
       function(results) {
         window.console.log('The guest script for a two-way comm channel has ' +
             'been injected into webview.');
         // Establish a communication channel with the guest.
         var msg = ['connect'];
         webview.contentWindow.postMessage(JSON.stringify(msg), '*');
       }
     );
   });
+  webview.addEventListener('consolemessage', function(e) {
+    window.console.log('Guest: "' + e.message + '"');
+  });
   window.addEventListener('message', function(e) {
     var data = JSON.parse(e.data);
     if (data[0] == 'connected') {
       console.log('A communication channel has been established with webview.');
       embedder.test.succeed();
       return;
     }
     console.log('Unexpected message: \'' + data[0]  + '\'');
     embedder.test.fail();
   });
@@ skipping 390 matching lines @@
   'testLoadDataAPI': testLoadDataAPI,
   'testResizeEvents': testResizeEvents
 };
 
 onload = function() {
   chrome.test.getConfig(function(config) {
     embedder.setUp_(config);
     chrome.test.sendMessage("Launched");
   });
 };