Video Player: fix misc bugs

ui/file_manager/video_player/js/cast/cast_video_element.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.
 
 'use strict';
 
 /**
  * Interval for updating media info (in ms).
  * @type {number}
  * @const
@@ skipping 243 matching lines @@
     // Resets the error code.
     this.errorCode_ = 0;
 
     Promise.all([
       sendTokenPromise,
       this.mediaManager_.getUrl(),
       this.mediaManager_.getMime(),
       this.mediaManager_.getThumbnail()]).
         then(function(results) {
           var url = results[1];
-          var mime = results[2];
-          var thumbnailUrl = results[3];
+          var mime = results[2];  // maybe empty
+          var thumbnailUrl = results[3];  // maybe empty
 
           this.mediaInfo_ = new chrome.cast.media.MediaInfo(url);
           this.mediaInfo_.contentType = mime;
           this.mediaInfo_.customData = {
             tokenRequired: true,
             thumbnailUrl: thumbnailUrl,
           };
 
           var request = new chrome.cast.media.LoadRequest(this.mediaInfo_);
           return new Promise(
@@ skipping 159 matching lines @@
       this.dispatchEvent(new Event('durationchange'));
     }
 
     // Media is being unloaded.
     if (!alive) {
       this.unloadMedia_();
       return;
     }
   },
 };