AudioPlayer.app: Migrate to Polymer 1.0.

ui/file_manager/audio_player/js/audio_player_model.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.
 
 /**
  * The model class for audio player.
  * @constructor
  */
-function AudioPlayerModel() {
+function AudioPlayerModel() {}
+
+AudioPlayerModel.prototype.initialize = function(callback) {
   'use strict';
 
   /**
    * List of values to be stored into the model.
    * @type {!Object<*>}
    * @const
    */
-  var VALUES = Object.freeze(
+  var VALUES =
     /**
      * They will be used as properties of AudioPlayerModel.
      * @lends {AudioPlayerModel.prototype}
      */
     {
       shuffle: false,
       repeat: false,
       volume: 100,
       expanded: false,
-    });
+    };
 
   /**
    * Prefix of the stored values in the storage.
    * @type {string}
    */
   var STORAGE_PREFIX = 'audioplayer-';
 
   /**
    * Save the values in the model into the storage.
    * @param {AudioPlayerModel} model The model.
    */
   function saveModel(model) {
     var objectToBeSaved = {};
     for (var key in VALUES) {
       objectToBeSaved[STORAGE_PREFIX + key] = model[key];
     }
 
     chrome.storage.local.set(objectToBeSaved);
   };
 
   /**
    * Load the values in the model from the storage.
    * @param {AudioPlayerModel} model The model.
-   * @param {function()} callback Called when the load is completed.
+   * @param {function()} inCallback Called when the load is completed.
    */
-  function loadModel(model, callback) {
+  function loadModel(model, inCallback) {
     // Restores the values from the storage
     var objectsToBeRead = Object.keys(VALUES).
                           map(function(a) {
                             return STORAGE_PREFIX + a;
                           });
 
     chrome.storage.local.get(objectsToBeRead, function(result) {
       for (var key in result) {
         // Strips the prefix.
         model[key.substr(STORAGE_PREFIX.length)] = result[key];
       }
-      callback();
+      inCallback();
     });
   };
 
   // Initializes values.
   for (var key in VALUES) {
     this[key] = VALUES[key];
   }
   Object.seal(this);
 
   // Restores the values from the storage
   var target = this;
   loadModel(target, function() {
     // Installs observer to watch changes of the values.
     Object.observe(target, function(changes) {
       saveModel(target);
     });
+    callback();
   });
 }