Expose always-on hotword preference via hotwordPrivate API.

chrome/test/data/extensions/api_test/hotword_private/alwaysOnEnabled/test.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.
 
 chrome.test.runTests([
-  function isAvailable() {
+  function alwaysOnEnabled() {
     chrome.hotwordPrivate.getStatus(
         chrome.test.callbackPass(function(result) {
-          chrome.test.sendMessage("available: " + result.available);
+          chrome.test.sendMessage("alwaysOnEnabled: " + result.alwaysOnEnabled);
     }));
   }
 ]);