<webview>: Implement WebRequest API

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 = {};
 
 // Creates a <webview> tag in document.body and returns the reference to it.
 // It also sets a dummy src. The dummy src is significant because this makes
 // sure that the <object> shim is created (asynchronously at this point) for the
 // <webview> tag. This makes the <webview> tag ready for add/removeEventListener
@@ skipping 391 matching lines @@
     // loaded.
     // TODO(fsamuel): Add a test to verify that subframe loads within a guest
     // do not fire the 'contentload' event.
     function webViewContentLoadEvent() {
       var webview = document.createElement('webview');
       webview.addEventListener('contentload', function(e) {
         chrome.test.succeed();
       });
       webview.setAttribute('src', 'data:text/html,trigger navigation');
       document.body.appendChild(webview);
+    },
+
+    function webViewWebRequestAPI() {
+      var webview = document.createElement('webview');
+      webview.setAttribute('src', 'data:text/html,trigger navigation');
+      var firstLoad = function() {
+        webview.removeEventListener('loadstop', firstLoad);
+        webview.onBeforeRequest.addListener(function(e) {
+          chrome.test.succeed();
+        }, { urls: ['<all_urls>']}, ['blocking']) ;
+        webview.src = windowOpenGuestURL;
+      };
+      webview.addEventListener('loadstop', firstLoad);
+      document.body.appendChild(webview);
     }
   ]);
 });