Add documentation for filtered events.

chrome/renderer/resources/extensions/web_request_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 bindings for the webRequest API.
 
 var webRequestNatives = requireNative('web_request');
 var GetUniqueSubEventName = webRequestNatives.GetUniqueSubEventName;
 
 var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
@@ skipping 12 matching lines @@
 //   ^ callback will only be called for onBeforeRequests matching the filter.
 function WebRequestEvent(eventName, opt_argSchemas, opt_extraArgSchemas,
                          opt_eventOptions) {
   if (typeof eventName != 'string')
     throw new Error('chrome.WebRequestEvent requires an event name.');
 
   this.eventName_ = eventName;
   this.argSchemas_ = opt_argSchemas;
   this.extraArgSchemas_ = opt_extraArgSchemas;
   this.subEvents_ = [];
-  this.eventOptions_ = opt_eventOptions ||
-      {'supportsListeners': true, 'supportsRules': false};
-
+  this.eventOptions_ = chromeHidden.parseEventOptions(opt_eventOptions);
   if (this.eventOptions_.supportsRules) {
     this.eventForRules_ =
         new chrome.Event(eventName, opt_argSchemas, opt_eventOptions);
   }
 };
 
 // Test if the given callback is registered for this event.
 WebRequestEvent.prototype.hasListener = function(cb) {
   if (!this.eventOptions_.supportsListeners)
     throw new Error('This event does not support listeners.');
@@ skipping 106 matching lines @@
 
 chromeHidden.registerCustomHook('webRequest', function(api) {
   var apiFunctions = api.apiFunctions;
 
   apiFunctions.setHandleRequest('handlerBehaviorChanged', function() {
     var args = Array.prototype.slice.call(arguments);
     sendRequest(this.name, args, this.definition.parameters,
                 {forIOThread: true});
   });
 });