[AudioPleyer] Fix repeat even when there is a single file in the list.

chrome/browser/resources/file_manager/audio_player/elements/audio_player.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';
 
 Polymer('audio-player', {
   /**
    * Child Elements
    */
@@ skipping 187 matching lines @@
    * @private
    */
   advance_: function(forward, repeat) {
     this.cancelAutoAdvance_();
 
     var nextTrackIndex = this.trackList.getNextTrackIndex(forward, true);
     var isNextTrackAvailable =
         (this.trackList.getNextTrackIndex(forward, repeat) !== -1);
 
     this.audioController.playing = isNextTrackAvailable;
+
+    // If there is only a single file in the list, 'currentTrackInde' is not
+    // changed and the handler is not invoked. Instead, plays here.
+    // TODO(yoshiki): clean up the code around here.
+    if (isNextTrackAvailable &&
+        this.trackList.currentTrackIndex == nextTrackIndex) {
+      this.audioElement.play();
+    }
+
     this.trackList.currentTrackIndex = nextTrackIndex;
 
     Platform.performMicrotaskCheckpoint();
   },
 
   /**
    * Timeout ID of auto advance. Used internally in scheduleAutoAdvance_() and
    *     cancelAutoAdvance_().
    * @type {number}
    * @private
@@ skipping 68 matching lines @@
     }
   },
 
   /**
    * Invoked when the audio player is being unloaded.
    */
   onPageUnload: function() {
     this.audioElement.src = '';  // Hack to prevent crashing.
   },
 });