Start and stop the hotword detector when the user opens/closes the launcher.

chrome/browser/resources/hotword/constants.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.constants', function() {
 'use strict';
 
 
 /**
  * Hotword data shared module extension's ID.
@@ skipping 64 matching lines @@
   REQUEST_MODEL: 'model',
   MODEL_LOADED: 'model_loaded',
   READY_FOR_AUDIO: 'audio',
   STOPPED: 'stopped',
   HOTWORD_DETECTED: 'hotword',
   MS_CONFIGURED: 'ms_configured'
 };
 
 
 /**
+ * Source of a hotwording session request.
+ * @enum {string}
+ */
+var SessionSource = {
+  LAUNCHER: 'launcher',
+  NTP: 'ntp',
+  GOOGLE_COM: 'google.com'

[rpetterson, 2014/09/10 17:53:31]

Where are the NTP and GOOGLE_COM ones currently (or will be) used?

[Anand Mistry (off Chromium), 2014/09/10 23:29:42]

They're not used in this change, so I've removed them and will add them back
when I need to. They will be used when I do the google.com/ntp integration.

+};
+
+
+/**
  * The browser UI language.
  * @const {string}
  */
 var UI_LANGUAGE = (chrome.i18n && chrome.i18n.getUILanguage) ?
       chrome.i18n.getUILanguage() : '';
 
 return {
   SHARED_MODULE_ID: SHARED_MODULE_ID,
   SHARED_MODULE_ROOT: SHARED_MODULE_ROOT,
   TimeoutMs: TimeoutMs,
   File: File,
   Error: Error,
   Event: Event,
   NaClPlugin: NaClPlugin,
+  SessionSource: SessionSource,
   UI_LANGUAGE: UI_LANGUAGE
 };
 
 });