[MD settings] change dropdown to accept array of objects rather than array of tuples

chrome/browser/resources/settings/controls/settings_dropdown_menu.js

 // Copyright 2015 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.
 
- /**
- * This tuple is made up of a (value, name, attribute). The value and name are
- * used by the dropdown menu. The attribute is optional 'user data' that is
- * ignored by the dropdown menu.
+/**
+ * The |name| is shown in the gui.  The |value| us use to set or compare with
+ * the preference value.
  * @typedef {{
- *   0: (number|string),
- *   1: string,
- *   2: (string|undefined)
+ *   name: string,
+ *   value: (number|string)
  * }}
  */
 var DropdownMenuOption;
 
 /**
  * @typedef {!Array<!DropdownMenuOption>}
  */
 var DropdownMenuOptionList;
 
 /**
@@ skipping 10 matching lines @@
  */
 Polymer({
   is: 'settings-dropdown-menu',
 
   properties: {
     /** A text label for the drop-down menu. */
     label: String,
 
     /**
      * List of options for the drop-down menu.
-     * TODO(michaelpg): use named properties instead of indices.
      * @type {DropdownMenuOptionList}
      */
     menuOptions: {
       type: Array,
       value: function() { return []; },
     },
 
     /**
      * A single Preference object being tracked.
      * @type {!chrome.settingsPrivate.PrefObject|undefined}
@@ skipping 78 matching lines @@
 
   /**
    * Updates the selected item when the pref or menuOptions change.
    * @private
    */
   updateSelected_: function() {
     if (!this.pref)
       return;
     var prefValue = this.pref.value;
     var option = this.menuOptions.find(function(menuItem) {
-      return menuItem[0] == prefValue;
+      return menuItem.value == prefValue;
     });
     if (option == undefined)
       this.selected_ = this.notFoundValue_;
     else
       this.selected_ = Settings.PrefUtil.prefToString(this.pref);
   },
 
   /**
    * @param {string} selected
    * @return {boolean}
    * @private
    */
   isSelectedNotFound_: function(selected) {
     return this.menuOptions && selected == this.notFoundValue_;
   },
 
   /**
    * @return {boolean}
    * @private
    */
   shouldDisableMenu_: function() {
     return this.disabled || !this.menuOptions.length;
   },
 });