Show a different banner in chrome://settings for extension-controlled settings.

chrome/browser/resources/options/content_settings_ui.js

 // Copyright (c) 2010 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.
 
 cr.define('options', function() {
 
   //////////////////////////////////////////////////////////////////////////////
   // ContentSettingsRadio class:
 
   // Define a constructor that uses an input element as its underlying element.
   var ContentSettingsRadio = cr.ui.define('input');
 
   ContentSettingsRadio.prototype = {
     __proto__: HTMLInputElement.prototype,
 
     /**
      * Initialization function for the cr.ui framework.
      */
     decorate: function() {
       this.type = 'radio';
       var self = this;
 
       this.addEventListener('change',
           function(e) {
             chrome.send('setContentFilter', [this.name, this.value]);
           });
     },
   };
 
+  /**
+   * Whether the content setting is controlled by something else than the user's
+   * settings (either 'policy' or 'extension').
+   * @type {string}
+   */
+  cr.defineProperty(ContentSettingsRadio, 'controlledBy', cr.PropertyKind.ATTR);
+
   //////////////////////////////////////////////////////////////////////////////
   // HandlersEnabledRadio class:
 
   // Define a constructor that uses an input element as its underlying element.
   var HandlersEnabledRadio = cr.ui.define('input');
 
   HandlersEnabledRadio.prototype = {
     __proto__: HTMLInputElement.prototype,
 
     /**
@@ skipping 11 matching lines @@
   };
 
   // Export
   return {
     ContentSettingsRadio: ContentSettingsRadio,
     HandlersEnabledRadio: HandlersEnabledRadio
   };
 
 });