Add <a is="action-link">, a web component extension of <a> for in-page actions.

chrome/browser/resources/ntp4/new_tab.css

 /* Copyright (c) 2012 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. */
 
 html {
   /* It's necessary to put this here instead of in body in order to get the
      background-size of 100% to work properly */
   height: 100%;
   overflow: hidden;
 }
@@ skipping 87 matching lines @@
 }
 
 .close-button:active {
   background-image: -webkit-image-set(
       url('../../../../ui/resources/default_100_percent/close_2_pressed.png')
           1x,
       url('../../../../ui/resources/default_200_percent/close_2_pressed.png')
           2x);
 }
 
-.link-button {
+[is='action-link'] {
   -webkit-margin-start: 0.5em;
 }
 
 #card-slider-frame {
   /* Must match #footer height. */
   bottom: 50px;
   overflow: hidden;
   /* We want this to fill the window except for the region used
    * by footer. */
   position: fixed;
@@ skipping 344 matching lines @@
   padding: 0;
 }
 
 .other-sessions-promo-message:only-child {
   display: block;
 }
 
 .other-sessions-promo-message p {
   margin: 0;
 }