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

chrome/browser/resources/hotword/constants.js

Index: chrome/browser/resources/hotword/constants.js
diff --git a/chrome/browser/resources/hotword/constants.js b/chrome/browser/resources/hotword/constants.js
index 2aab1ed79f621055f0c26e8cf051bf1fa447750a..19def367275efa05e669e4552a4f0bd31ac69ec8 100644
--- a/chrome/browser/resources/hotword/constants.js
+++ b/chrome/browser/resources/hotword/constants.js
@@ -5,7 +5,6 @@
 cr.define('hotword.constants', function() {
 'use strict';
 
-
 /**
  * Hotword data shared module extension's ID.
  * @const {string}
@@ -13,14 +12,12 @@ cr.define('hotword.constants', function() {
  */
 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}
@@ -31,7 +28,6 @@ var TimeoutMs = {
   LONG: 2000
 };
 
-
 /**
  * The URL of the files used by the plugin.
  * @enum {string}
@@ -40,7 +36,6 @@ var File = {
   RECOGNIZER_CONFIG: 'hotword.data',
 };
 
-
 /**
  * Errors emitted by the NaClManager.
  * @enum {string}
@@ -50,7 +45,6 @@ var Error = {
   TIMEOUT: 'timeout',
 };
 
-
 /**
  * Event types supported by NaClManager.
  * @enum {string}
@@ -61,7 +55,6 @@ var Event = {
   ERROR: 'error',
 };
 
-
 /**
  * Messages for communicating with the NaCl recognizer plugin. These must match
  * constants in <google3>/hotword_plugin.c
@@ -80,6 +73,13 @@ var NaClPlugin = {
   MS_CONFIGURED: 'ms_configured'
 };
 
+/**
+ * Source of a hotwording session request.
+ * @enum {string}
+ */
+var SessionSource = {
+  LAUNCHER: 'launcher'
+};
 
 /**
  * The browser UI language.
@@ -96,6 +96,7 @@ return {
   Error: Error,
   Event: Event,
   NaClPlugin: NaClPlugin,
+  SessionSource: SessionSource,
   UI_LANGUAGE: UI_LANGUAGE
 };