Add fallback mechanism to release Extension ports if the JS context has been destroyed.

extensions/renderer/resources/guest_view/web_view/web_view_action_requests.js

 // Copyright 2014 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.
 
 // This module implements helper objects for the dialog, newwindow, and
 // permissionrequest <webview> events.
 
 var MessagingNatives = requireNative('messaging_natives');
 var WebViewConstants = require('webViewConstants').WebViewConstants;
 var WebViewInternal = require('webViewInternal').WebViewInternal;
@@ skipping 48 matching lines @@
   var defaultPrevented = !this.webViewImpl.dispatchEvent(this.webViewEvent);
   // Set |webViewEvent| to null to break the circular reference to |request| so
   // that the garbage collector can eventually collect it.
   this.webViewEvent = null;
   if (this.actionTaken) {
     return;
   }
 
   if (defaultPrevented) {
     // Track the lifetime of |request| with the garbage collector.
-    MessagingNatives.BindToGC(request, this.defaultAction.bind(this));
+    var portId = -1;  // (hack) there is no Extension Port to release
+    MessagingNatives.BindToGC(request, this.defaultAction.bind(this), portId);
   } else {
     this.defaultAction();
   }
 };
 
 // Displays a warning message when an action request is blocked by default.
 WebViewActionRequest.prototype.showWarningMessage = function() {
   window.console.warn(this.WARNING_MSG_REQUEST_BLOCKED);
 };
 
@@ skipping 200 matching lines @@
 var WebViewActionRequests = {
   WebViewActionRequest: WebViewActionRequest,
   Dialog: Dialog,
   NewWindow: NewWindow,
   PermissionRequest: PermissionRequest,
   FullscreenPermissionRequest: FullscreenPermissionRequest
 };
 
 // Exports.
 exports.WebViewActionRequests = WebViewActionRequests;