Font Settings API: Use Chrome settings CSS in sample extension.

chrome/common/extensions/docs/examples/api/fontSettings/css/chrome_shared.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. */
 
-/* This file holds CSS that should be shared, in theory, by all user-visible
- * chrome:// pages. */
-
-@import url("chrome://resources/css/widgets.css");
-<if expr="pp_ifdef('chromeos')">
-  @import url("chrome://resources/css/chromeos/ui_account_tweaks.css");
-</if>
+/* Copy of /resources/shared/css/chrome_shared.css for sample extension. */
 
 /* Prevent CSS from overriding the hidden property. */
 [hidden] {
   display: none !important;
 }
 
 html.loading * {
   -webkit-transition-delay: 0 !important;
   -webkit-transition-duration: 0 !important;
 }
@@ skipping 75 matching lines @@
 }
 
 /* WebKit does not honor alignment for text specified via placeholder attribute.
  * This CSS is a workaround. Please remove once WebKit bug is fixed.
  * https://bugs.webkit.org/show_bug.cgi?id=63367
  */
 html[dir='rtl'] input.weakrtl::-webkit-input-placeholder,
 html[dir='rtl'] .weakrtl input::-webkit-input-placeholder {
   direction: rtl;
 }