Hotword Private API: Adds speech training functions.

chrome/test/data/extensions/api_test/hotword_private/stopTraining/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 setEnabledFalse() {
-    chrome.hotwordPrivate.setEnabled(
-        false, chrome.test.callbackPass(function() {
-          chrome.test.sendMessage("ready");
+  function stopTraining() {
+    chrome.hotwordPrivate.stopTraining(chrome.test.callbackPass(function() {
+          chrome.test.sendMessage("stop training");
         }));
   }
 ]);