MD Settings: add extension-controlled indicator to homepage

chrome/browser/resources/settings/appearance_page/appearance_page.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.
 
 /**
  * 'settings-appearance-page' is the settings page containing appearance
  * settings.
  *
  * Example:
  *
@@ skipping 128 matching lines @@
       return this.i18n('homePageNtp');
     return homepage || this.i18n('exampleDotCom');
   },
 
   /** @private */
   onCustomizeFontsTap_: function() {
     settings.navigateTo(settings.Route.FONTS);
   },
 
   /** @private */
+  onDisableExtension_: function() {
+    this.fire('refresh-pref', 'homepage');
+  },
+
+  /** @private */
   onThemesTap_: function() {
     window.open(this.themeUrl_ || loadTimeData.getString('themesGalleryUrl'));
   },
 
 <if expr="chromeos">
   /**
    * ChromeOS only.
    * @private
    */
   openWallpaperManager_: function() {
@@ skipping 99 matching lines @@
    * @see content::ZoomValuesEqual().
    * @param {number} zoom1
    * @param {number} zoom2
    * @return {boolean}
    * @private
    */
   zoomValuesEqual_: function(zoom1, zoom2) {
     return Math.abs(zoom1 - zoom2) <= 0.001;
   },
 });