Remove hard-coded font families in WebUI.

chrome/browser/resources/local_ntp/local_ntp.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. */
 body {
   background-attachment: fixed !important;
   background-color: white;
   cursor: default;
-  font-family: arial, sans-serif;
-  font-size: small;
   margin: 0;
   overflow-x: hidden;
 }
 
 #ntp-contents {
   text-align: -webkit-center;
 }
 
 .non-google-page #ntp-contents {
   position: absolute;
@@ skipping 78 matching lines @@
 
 html[dir=rtl] #fakebox > input {
   padding-left: 0;
   padding-right: 8px;
   right: 0;
 }
 
 #fakebox-text {
   bottom: 0;
   color: #bbb;
-  font-family: arial, sans-serif;
   font-size: 16px;
   left: 9px;
   margin-top: 1px;
   overflow: hidden;
   position: absolute;
   right: 9px;
   text-align: initial;
   text-overflow: ellipsis;
   top: 0;
   vertical-align: middle;
@@ skipping 565 matching lines @@
   text-align: right;
 }
 
 #recent-tabs {
   background: #fff;
   border: 1px solid #c0c0c0;
   border-radius: 2px;
   bottom: 0;
   color: rgb(17, 85, 204);
   cursor: pointer;
-  font-family: Arial;
   font-size: 14px;
   opacity: 0.9;
   padding: 3px;
   position: fixed;
   right: 8px;
 }
 
 html[dir=rtl] #attribution,html[dir=rtl] #recent-tabs {
   left: 8px;
   right: auto;
 }