Play a chime when the hotword is triggered.

chrome/browser/resources/hotword/state_manager.js

 // Copyright (c) 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.
 
 cr.define('hotword', function() {
   'use strict';
 
   /**
    * Class to manage hotwording state. Starts/stops the hotword detector based
    * on user settings, session requests, and any other factors that play into
@@ skipping 25 matching lines @@
      * @private {?hotword.constants.SessionSource}
      */
     this.sessionSource_ = null;
 
     /**
      * Callback to run when the hotword detector has successfully started.
      * @private {!function()}
      */
     this.sessionStartedCb_ = null;
 
+    /**
+     * Hotword trigger audio notification... a.k.a The Chime (tm)

[rpetterson, 2014/09/16 07:55:45]

nit: end with period.

+     * @private {!Audio}
+     */
+    this.chime_ = document.createElement('audio');
+
     // Get the initial status.
     chrome.hotwordPrivate.getStatus(this.handleStatus_.bind(this));
+
+    // Setup the chime and insert into the page.
+    this.chime_.src = chrome.extension.getURL('chime.wav');
+    document.body.appendChild(this.chime_);
   }
 
   /**
    * @enum {number}
    * @private
    */
   StateManager.State_ = {
     STOPPED: 0,
     STARTING: 1,
     RUNNING: 2,
@@ skipping 162 matching lines @@
 
     /**
      * Handle hotword triggering.
      * @private
      */
     onTrigger_: function() {
       assert(this.pluginManager_);
       // Detector implicitly stops when the hotword is detected.
       this.state_ = State_.STOPPED;
 
+      // Play the chime.
+      this.chime_.play();
+
       chrome.hotwordPrivate.notifyHotwordRecognition('search', function() {});
 
       // Implicitly clear the session. A session needs to be started in order to
       // restart the detector.
       this.sessionSource_ = null;
       this.sessionStartedCb_ = null;
     },
 
     /**
      * Start a hotwording session.
@@ skipping 17 matching lines @@
       this.sessionSource_ = null;
       this.sessionStartedCb_ = null;
       this.updateStateFromStatus_();
     }
   };
 
   return {
     StateManager: StateManager
   };
 });