Ensure that privates are private.

extensions/renderer/resources/event.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.
 
   var exceptionHandler = require('uncaught_exception_handler');
   var eventNatives = requireNative('event_natives');
   var logging = requireNative('logging');
   var schemaRegistry = requireNative('schema_registry');
   var sendRequest = require('sendRequest').sendRequest;
   var utils = require('utils');
@@ skipping 472 matching lines @@
     validate([this.webViewInstanceId, ruleIdentifiers, cb],
              $Array.splice(
                  $Array.slice(ruleFunctionSchemas.getRules.parameters), 1));
 
     sendRequest(
       "events.getRules",
       [this.eventName, this.webViewInstanceId, ruleIdentifiers, cb],
       ruleFunctionSchemas.getRules.parameters);
   }
 
-  var Event = utils.expose('Event', EventImpl, { functions: [
-    'addListener',
-    'removeListener',
-    'hasListener',
-    'hasListeners',
-    'dispatchToListener',
-    'dispatch',
-    'addRules',
-    'removeRules',
-    'getRules'
-  ] });
+  function Event() {
+    privates(Event).constructPrivate(this, arguments);
+  }
+  utils.expose(Event, EventImpl, {
+    functions: [
+      'addListener',
+      'removeListener',
+      'hasListener',
+      'hasListeners',
+      'dispatchToListener',
+      'dispatch',
+      'addRules',
+      'removeRules',
+      'getRules',
+    ],
+  });
 
   // NOTE: Event is (lazily) exposed as chrome.Event from dispatcher.cc.
   exports.$set('Event', Event);
 
   exports.$set('dispatchEvent', dispatchEvent);
   exports.$set('parseEventOptions', parseEventOptions);
   exports.$set('registerArgumentMassager', registerArgumentMassager);