Move Declarative Web Request API out of experimental and make it a feature

chrome/renderer/resources/extensions/declarative_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 declarative API.
 
 var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 var sendRequest = require('sendRequest').sendRequest;
 
-chromeHidden.registerCustomHook('experimental.declarative',
+chromeHidden.registerCustomHook('declarative',
                                 function(bindingsAPI) {
   var apiFunctions = bindingsAPI.apiFunctions;
   var apiDefinitions = bindingsAPI.apiDefinitions;
   var cachedEventOptions = {};
 
   function getEventOptions(qualifiedEventName) {
     if (cachedEventOptions[qualifiedEventName])
       return cachedEventOptions[qualifiedEventName];
 
     // Parse qualifiedEventName into namespace and event name.
@@ skipping 46 matching lines @@
       throw new Error('Event ' + eventName + ' misses conditions or ' +
                       'actions in the API specification.');
     }
     validateRules(rules,
                   eventOptions.conditions,
                   eventOptions.actions);
     sendRequest(this.name, [eventName, rules, opt_callback],
                 this.definition.parameters);
   });
 });