Add link to the Advanced Font Settings extension in Font Settings

chrome/browser/resources/options/font_settings.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. */
 
 #font-settings > section {
   overflow: hidden;
 }
 
+#font-settings .action-area {
+  -webkit-box-pack: start;
+}
+
+#font-settings .action-area .spacer {
+  -webkit-box-flex: 1;
+  display: -webkit-box;
+}
+
+#font-settings .button-strip {
+  width: 100%;
+}
+
 .font-setting-container {
   display: -webkit-box;
 }
 
 #font-settings input[type='range'] {
   width: 100%;
 }
 
 #minimum-font-sample {
   height: 35px;
@@ skipping 21 matching lines @@
   width: 270px;
 }
 
 .font-settings-huge {
   float: right;
 }
 
 html[dir=rtl] .font-settings-huge {
   float: left;
 }