fix appearance of buttons in chrome://settings

chrome/browser/resources/options/chromeos/accounts_user_list.js

 // Copyright (c) 2011 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.accounts', function() {
   const List = cr.ui.List;
   const ListItem = cr.ui.ListItem;
   const ArrayDataModel = cr.ui.ArrayDataModel;
 
   /**
@@ skipping 173 matching lines @@
       emailNameBlock.appendChild(labelName);
       emailNameBlock.title = this.user.owner ?
           localStrings.getStringF('username_format', this.user.email) :
           this.user.email;
 
       this.appendChild(this.icon_);
       this.appendChild(emailNameBlock);
 
       if (!this.user.owner) {
         var removeButton = this.ownerDocument.createElement('button');
-        removeButton.classList.add('raw-button');
-        removeButton.classList.add('remove-user-button');
+        removeButton.className =
+            'raw-button remove-user-button custom-appearance';
         this.appendChild(removeButton);
       }
     },
 
     /**
      * Reloads user picture.
      */
     updatePicture: function() {
       this.icon_.src = 'chrome://userimage/' + this.user.email +
                        '?id=' + (new Date()).getTime();
     }
   };
 
   return {
     UserList: UserList
   };
 });