Ensure that privates are private.

extensions/renderer/resources/web_request_internal_custom_bindings.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.
 
 // Custom binding for the webRequestInternal API.
 
 var binding = require('binding').Binding.create('webRequestInternal');
 var eventBindings = require('event_bindings');
 var sendRequest = require('sendRequest').sendRequest;
 var validate = require('schemaUtils').validate;
@@ skipping 157 matching lines @@
                 {forIOThread: true});
   });
 
   apiFunctions.setHandleRequest('eventHandled', function() {
     var args = $Array.slice(arguments);
     sendRequest(this.name, args, this.definition.parameters,
                 {forIOThread: true});
   });
 });
 
-var WebRequestEvent = utils.expose('WebRequestEvent',
-                                   WebRequestEventImpl,
-                                   { functions: [
-  'hasListener',
-  'hasListeners',
-  'addListener',
-  'removeListener',
-  'addRules',
-  'removeRules',
-  'getRules'
-] });
+function WebRequestEvent() {
+  privates(WebRequestEvent).constructPrivate(this, arguments);
+}
+utils.expose(WebRequestEvent, WebRequestEventImpl, {
+  functions: [
+    'hasListener',
+    'hasListeners',
+    'addListener',
+    'removeListener',
+    'addRules',
+    'removeRules',
+    'getRules',
+  ],
+});
 
 webRequestInternal = binding.generate();
 exports.$set('binding', webRequestInternal);

[Devlin, 2016/04/22 18:52:46]

nit: since you're here, may as well inline the binding.generate() call

[robwu, 2016/04/22 20:33:43]

webRequestInternal is also used internally within this file, so this should stay
as a separate variable.

 exports.$set('WebRequestEvent', WebRequestEvent);