MD Settings: clarify "controlled by" logic

ui/webui/resources/cr_elements/policy/cr_policy_indicator_behavior.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.
 
 /**
  * @fileoverview Behavior for policy controlled indicators.
  */
 
 /** @enum {string} */
 var CrPolicyIndicatorType = {
   DEVICE_POLICY: 'devicePolicy',
-  EXTENSION: 'extension',
   NONE: 'none',
   OWNER: 'owner',
   PRIMARY_USER: 'primary_user',
   RECOMMENDED: 'recommended',
   USER_POLICY: 'userPolicy',
 };
 
 /** @polymerBehavior */
 var CrPolicyIndicatorBehavior = {
   /**
@@ skipping 19 matching lines @@
         icon = 'group';
         break;
       case CrPolicyIndicatorType.OWNER:
         icon = 'person';
         break;
       case CrPolicyIndicatorType.USER_POLICY:
       case CrPolicyIndicatorType.DEVICE_POLICY:
       case CrPolicyIndicatorType.RECOMMENDED:
         icon = 'domain';
         break;
-      case CrPolicyIndicatorType.EXTENSION:
-        icon = 'extension';
-        break;
       default:
         assertNotReached();
     }
     return 'cr:' + icon;
   },
 
   /**
    * @param {string} id The id of the string to translate.
    * @param {string=} opt_name An optional name argument.
    * @return The translated string.
    */
   i18n_: function (id, opt_name) {
     return loadTimeData.getStringF(id, opt_name);
   },
 
   /**
    * @param {CrPolicyIndicatorType} type
    * @param {string} name The name associated with the controllable. See
-   *     chrome.settingsPrivate.PrefObject.policySourceName
+   *     chrome.settingsPrivate.PrefObject.controlledByName
    * @return {string} The tooltip text for |type|.
    */
   getPolicyIndicatorTooltip: function(type, name) {
     switch (type) {
       case CrPolicyIndicatorType.PRIMARY_USER:
         return this.i18n_('controlledSettingShared', name);
       case CrPolicyIndicatorType.OWNER:
         return this.i18n_('controlledSettingOwner', name);
       case CrPolicyIndicatorType.USER_POLICY:
       case CrPolicyIndicatorType.DEVICE_POLICY:
         return this.i18n_('controlledSettingPolicy');
-      case CrPolicyIndicatorType.EXTENSION:
-        return this.i18n_('controlledSettingExtension', name);
       case CrPolicyIndicatorType.RECOMMENDED:
         // This case is not handled here since it requires knowledge of the
         // value and recommended value associated with the controllable.
         assertNotReached();
     }
     return '';
   }
 };