Add reset all button to flags page

chrome/browser/resources/flags.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. */
 
 body {
   margin: 10px;
 <if expr="not pp_ifdef('android')">
   min-width: 47em;
 </if>
   /* Should match needs-restart.height + 5 */
@@ skipping 45 matching lines @@
   color: red;
   font-weight: bold;
 }
 
 div.content {
   font-size: 88%;
   margin-top: 5px;
 }
 
 .section-header {
-  -webkit-padding-start: 5px;
   background: rgb(235, 239, 249);
   border-top: 1px solid rgb(181, 199, 222);
   font-size: 99%;
-  padding-bottom: 2px;
-  padding-top: 3px;
+  padding: 2px 5px 3px;
   width: 100%;
 }
 
 .section-header > table tr td:first-child {
   width: 100%;
 }
 
 .section-header > table {
   width: 100%;
 }
 
 .section-header-title {
   font-weight: bold;
+  line-height: 200%;
+}
+
+#experiment-reset-all {
+  float: right;
+}
+
+html[dir=rtl] #experiment-reset-all {
+  float: left;
 }
 
 .vbox-container {
   -webkit-box-orient: vertical;
   display: -webkit-box;
 }
 
 .wbox {
   -webkit-box-align: stretch;
   -webkit-box-flex: 1;
@@ skipping 62 matching lines @@
   padding-right: 15px;
   padding-top: 15px;
   position: fixed;
   width: 100%;
 }
 
 button {
   font-size: 104%;
 }