Separate the audio player app from Files.app

ui/file_manager/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.
-
-(function(global) {
-  'use strict';
-
-  /**
-   * List of values to be stored into the model.
-   * @type {Object<string, *>}
-   * @const
-   */
-  var VALUES = Object.freeze({
-    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.
-   */
-  function loadModel(model, callback) {
-    // 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();
-    }.bind(this));
-  };
-
-  /**
-   * The model class for audio player.
-   * @constructor
-   */
-  function AudioPlayerModel() {
-    // Initializes values.
-    for (var key in VALUES) {
-      this[key] = VALUES[key];
-    }
-    Object.seal(this);
-
-    // Restores the values from the storage
-    loadModel(this, function() {
-      // Installs observer to watch changes of the values.
-      var observer = new ObjectObserver(this);
-      observer.open(function(added, removed, changed, getOldValueFn) {
-        saveModel(this);
-      }.bind(this));
-    }.bind(this));
-  }
-
-  // Exports AudioPlayerModel class to the global.
-  global.AudioPlayerModel = AudioPlayerModel;
-
-})(this || window);