Enable the accessibility audit for chrome://net-internals

chrome/browser/resources/net_internals/timeline_view.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.
  */
 
 #timeline-view-selection-div {
   display: inline-block;
   overflow-y: auto;
 }
 
 #timeline-view-selection-toggle {
-  cursor: pointer;
+  background-color: #fff;
+  background-image: url(chrome://resources/images/select.png);
+  border: none;
+  height: 8px;
+  padding: none;
+  width: 19px;
 }
 
 .timeline-view-rotateleft {
   -webkit-transform: rotate(90deg);
 }
 
 .timeline-view-rotateright {
   -webkit-transform: rotate(270deg);
 }
 
@@ skipping 62 matching lines @@
 }
 
 #timeline-view-scrollbar-div {
   overflow-x: scroll;
   overflow-y: hidden;
 }
 
 #timeline-view-scrollbar-inner-div {
   height: 1px;
 }