<webview>: First stab at implementing media permission request for guests.

chrome/renderer/resources/extensions/web_view.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.
 
 // Shim that simulates a <webview> tag via Mutation Observers.
 //
 // The actual tag is implemented via the browser plugin. The internals of this
 // are hidden via Shadow DOM.
 
 var watchForTag = require("tagWatcher").watchForTag;
@@ skipping 111 matching lines @@
       console.error('contentWindow is not available at this time. ' +
           'It will become available when the page has finished loading.');
     },
     // No setter.
     enumerable: true
   });
 
   for (var eventName in WEB_VIEW_EVENTS) {
     this.setupEvent_(eventName, WEB_VIEW_EVENTS[eventName]);
   }
+  this.maybeSetupPermissionEvent_();
 }
 
 /**
  * @private
  */
 WebView.prototype.handleMutation_ = function(mutation) {
   // This observer monitors mutations to attributes of the <webview> and
   // updates the BrowserPlugin properties accordingly. In turn, updating
   // a BrowserPlugin property will update the corresponding BrowserPlugin
   // attribute, if necessary. See BrowserPlugin::UpdateDOMAttribute for more
@@ skipping 34 matching lines @@
 WebView.prototype.setupEvent_ = function(eventname, attribs) {
   var node = this.node_;
   this.objectNode_.addEventListener('-internal-' + eventname, function(e) {
     var evt = new Event(eventname, { bubbles: true });
     var detail = e.detail ? JSON.parse(e.detail) : {};
     attribs.forEach(function(attribName) {
       evt[attribName] = detail[attribName];
     });
     node.dispatchEvent(evt);
   });
-}
+};
+
+/**
+ * Implemented when experimental permission is available.
+ * @private
+ */
+WebView.prototype.maybeSetupPermissionEvent_ = function() {};
+
+exports.WebView = WebView;