[MD settings] controlled by extension icon on default font size

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.
 
 /**
  * The |name| is shown in the gui.  The |value| us use to set or compare with
  * the preference value.
  * @typedef {{
  *   name: string,
  *   value: (number|string)
@@ skipping 11 matching lines @@
  * in the settings.
  *
  * Example:
  *
  *   <settings-dropdown-menu pref="{{prefs.foo}}">
  *   </settings-dropdown-menu>
  */
 Polymer({
   is: 'settings-dropdown-menu',
 
+  behaviors: [CrPolicyPrefBehavior, PrefControlBehavior],
+
   properties: {
     /**
      * List of options for the drop-down menu.
      * @type {?DropdownMenuOptionList}
      */
     menuOptions: {
       type: Array,
       value: null,
     },
 
     /** Whether the dropdown menu should be disabled. */
     disabled: {
       type: Boolean,
       reflectToAttribute: true,
       value: false,
     },
 
     /**
      * The value of the "custom" item.
      * @private
      */
     notFoundValue_: {
       type: String,
       value: 'SETTINGS_DROPDOWN_NOT_FOUND_ITEM',
       readOnly: true,
     },
   },
 
-  behaviors: [
-    PrefControlBehavior,
-  ],
-
   observers: [
     'updateSelected_(menuOptions, pref.value)',
   ],
 
   /**
    * Pass the selection change to the pref value.
    * @private
    */
   onChange_: function() {
     var selected = this.$.dropdownMenu.value;
@@ skipping 44 matching lines @@
       return menuItem.value == prefValue;
     });
     return !option;
   },
 
   /**
    * @return {boolean}
    * @private
    */
   shouldDisableMenu_: function() {
-    return this.disabled || this.menuOptions === null ||
-        this.menuOptions.length == 0;
+    return this.disabled || this.isPrefEnforced() ||
+        this.menuOptions === null || this.menuOptions.length == 0;
   },
 });