Mark supervised users in the "Users" list in about:settings.

chrome/browser/resources/options/browser_options.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. */
 
 #change-home-page-section {
   margin-left: 30px;
 }
 
 #home-page-url {
   display: inline-block;
@@ skipping 69 matching lines @@
 
 #sync-buttons {
   clear: both;
 }
 
 #profiles-list {
   margin-bottom: 10px;
   min-height: 0;
 }
 
+#profiles-list .profile-container {
+  -webkit-box-align: center;
+  display: -webkit-box;
+  max-width: 100%;
+  white-space: nowrap;

[Patrick Dubroy, 2014/04/03 10:48:39]

I don't think you need this.

[Marc Treib, 2014/04/03 11:41:56]

Done.

+}
+
 #profiles-list .profile-name {
   -webkit-box-flex: 1;
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
 }
 
+#profiles-list .profile-supervised {
+  color: gray;

[Patrick Dubroy, 2014/04/03 10:48:39]

I don't see "gray" anywhere else in this file. Usually we use rgb or hex values
for colors...is there another element on this page with the same color that you
could be consistent with?

[Marc Treib, 2014/04/03 11:41:56]

I don't see another "gray for de-emphasis" anywhere else on the page, and
reusing a "gray for disabled" color doesn't make much sense. I could just
replace it by, say, #777 if named colors are discouraged in general? ("white"
and "black" do appear in this file, though!)

[Patrick Dubroy, 2014/04/03 11:48:38]

Actually, we seem to use #999 in a few places (e.g., policy-controlled
settings), and in the sidebar menu. Maybe this should be the same?

[Marc Treib, 2014/04/03 12:01:08]

Done.

+  margin-left: 5px;
+  white-space: nowrap;

[Patrick Dubroy, 2014/04/03 10:48:39]

Ditto.

[Marc Treib, 2014/04/03 11:41:56]

Done.

+}
+
 #profiles-list > * {
   height: 40px;
 }
 
 #profiles-list:focus {
   border-color: rgb(77, 144, 254);
 }
 
 .profile-img {
   height: 31px;
@@ skipping 315 matching lines @@
 }
 
 #accessibility-autoclick .controlled-setting-with-label {
   -webkit-box-align: baseline;
 }
 
 #accessibility-autoclick label + select {
   /* Same as .controlled-setting-with-label > input + span. */
   -webkit-margin-start: 0.6em;
 }