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.
  * @const {string}
  * TODO(amistry): Replace with real shared module ID.
  */
 var SHARED_MODULE_ID = 'bepbmhgboaologfdajaanbcjmnhjmhfn';
 
-
 /**
  * Path to shared module data.
  * @const {string}
  */
 var SHARED_MODULE_ROOT = '_modules/' + SHARED_MODULE_ID;
 
-
 /**
  * Time to wait for expected messages, in milliseconds.
  * @enum {number}
  */
 var TimeoutMs = {
   SHORT: 200,
   NORMAL: 500,
   LONG: 2000
 };
 
-
 /**
  * The URL of the files used by the plugin.
  * @enum {string}
  */
 var File = {
   RECOGNIZER_CONFIG: 'hotword.data',
 };
 
-
 /**
  * Errors emitted by the NaClManager.
  * @enum {string}
  */
 var Error = {
   NACL_CRASH: 'nacl_crash',
   TIMEOUT: 'timeout',
 };
 
-
 /**
  * Event types supported by NaClManager.
  * @enum {string}
  */
 var Event = {
   READY: 'ready',
   TRIGGER: 'trigger',
   ERROR: 'error',
 };
 
-
 /**
  * Messages for communicating with the NaCl recognizer plugin. These must match
  * constants in <google3>/hotword_plugin.c
  * @enum {string}
  */
 var NaClPlugin = {
   RESTART: 'r',
   SAMPLE_RATE_PREFIX: 'h',
   MODEL_PREFIX: 'm',
   STOP: 's',
   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'
+};
 
 /**
  * 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
 };
 
 });