Make Chrome OS Audio Player survive page reload and OS restart.

chrome/browser/resources/file_manager/js/mock_chrome.js

 // Copyright (c) 2012 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 MockEventSource() {
   this.listeners_ = [];
 }
 
 /**
  * Add a listener.
@@ skipping 795 matching lines @@
 
 /**
  * Mock object for |chrome.mediaPlayerPrivate|.
  */
 chrome.mediaPlayerPrivate = {
 
   onPlaylistChanged: new MockEventSource(),
 
   onTogglePlayState: new MockEventSource(),
 
+  onNextTrack: new MockEventSource(),
+
+  onPrevTrack: new MockEventSource(),
+
   play: function(urls, position) {
     this.playlist_ = { items: urls, position: position };
 
     if (this.popup_) {
       this.onPlaylistChanged.notify();
       return;
     }
 
     // Using global document is OK for the test harness.
     this.popup_ = document.createElement('iframe');
@@ skipping 19 matching lines @@
 
   setWindowHeight: function(height) {
     this.popup_.style.height = height + 'px';
   },
 
   closeWindow: function() {
     this.popup_.parentNode.removeChild(this.popup_);
     this.popup_ = null;
   }
 };