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

chrome/browser/resources/hotword/manager.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.
 
 (function() {
   'use strict';
 
   /**
    * @fileoverview This extension provides hotword triggering capabilites to
    * Chrome.
@@ skipping 25 matching lines @@
     if (info.id == hotword.constants.SHARED_MODULE_ID)
       chrome.runtime.reload();
   });
 
   // Detect when a session has requested to be started and stopped.
   chrome.hotwordPrivate.onHotwordSessionRequested.addListener(function() {
     // TODO(amistry): This event should change state depending on whether the
     // user has enabled always-on hotwording. But for now, always signal the
     // start of a hotwording session. This allows this extension to work with
     // the app launcher in the current state.
-    chrome.hotwordPrivate.setHotwordSessionState(true, function() {});
+    stateManager.startSession(
+        hotword.constants.SessionSource.LAUNCHER,
+        function() {
+          chrome.hotwordPrivate.setHotwordSessionState(true, function() {});
+        });
   });
 
   chrome.hotwordPrivate.onHotwordSessionStopped.addListener(function() {
+    stateManager.stopSession(hotword.constants.SessionSource.LAUNCHER);
     chrome.hotwordPrivate.setHotwordSessionState(false, function() {});
   });
 }());