[Audio Player] Cleanup the code along with closure compiler

ui/file_manager/audio_player/elements/audio_player.js

Index: ui/file_manager/audio_player/elements/audio_player.js
diff --git a/ui/file_manager/audio_player/elements/audio_player.js b/ui/file_manager/audio_player/elements/audio_player.js
index c01104ad1e9b561ded8c2465353c375eff91fc46..990513f2f2c04c422e111bca8a68983a5ab106e0 100644
--- a/ui/file_manager/audio_player/elements/audio_player.js
+++ b/ui/file_manager/audio_player/elements/audio_player.js
@@ -2,14 +2,23 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-Polymer('audio-player', {
-  /**
-   * Child Elements
-   */
+/**
+ * @constructor
+ * @extends {PolymerElement}
+ */
+var AudioPlayerElement = function() {};
+
+AudioPlayerElement.prototype = {
+  // Child Elements
   audioController: null,
   audioElement: null,
   trackList: null,
 
+  // Published values
+  playing: true,
+  currenttrackurl: '',
+  playcount: 0,
+
   // Attributes of the element (lower characters only).
   // These values must be used only to data binding and shouldn't be assigned
   // any value nowhere except in the handler.
@@ -244,7 +253,7 @@ Polymer('audio-player', {
   /**
    * Timeout ID of auto advance. Used internally in scheduleAutoAdvance_() and
    *     cancelAutoAdvance_().
-   * @type {number}
+   * @type {number?}
    * @private
    */
   autoAdvanceTimer_: null,
@@ -375,4 +384,6 @@ Polymer('audio-player', {
         break;
     }
   },
-});
+};
+
+Polymer('audio-player', AudioPlayerElement.prototype);