Remove hard-coded font families in WebUI.

chrome/browser/resources/sync_internals/about.css

 /* Copyright 2013 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.
- */
+ * found in the LICENSE file. */
 
 #about-info {
   -webkit-column-width: 350px;
 }
 
 #about-info > div {
   -webkit-column-break-inside: avoid;
   width: 350px;
 }
 
@@ skipping 97 matching lines @@
   border: 2px outset;
   padding: 0.5em;
 }
 
 .traffic-event-entry:hover {
   background-color: #eee;
 }
 
 .traffic-event-entry .time {
   color: #222;
-  font-family: sans-serif;
 }
 
 .traffic-event-entry .type {
-  font-family: sans-serif;
   font-weight: bold;
   margin: 0.5em;
   white-space: nowrap;
 }
 
 .traffic-event-entry .details {
   margin: 0.5em;
   overflow-x: auto;
 }
 
 .traffic-event-entry .proto {
   display: none;
 }
 
 .traffic-event-entry-expanded .proto {
   background-color: #fff;
   border: 1px solid #222;
   display: block;
   max-height: 300px;
   overflow-x: auto;
   overflow-y: auto;
 }