Disable modifying extensions when in managed mode.

chrome/browser/resources/options2/options_page.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 {
   position: relative;
 }
 
 #main-content {
   bottom: 0;
@@ skipping 91 matching lines @@
   right: 0;
 }
 
 /* Omit top padding (currently only on #settings) whenever the search page is
  * showing.
  */
 #searchPage:not([hidden]) + #settings {
   padding-top: 0;
 }
 
-.managed-prefs-banner {
-  background-color: white;
-  width: 100%;
-  z-index: 2;
-}
-
-.page:not(.showing-banner) .managed-prefs-banner {
-  display: none;
-}
-
-.managed-prefs-gradient {
-  background: -webkit-linear-gradient(rgb(255, 242, 183),
-                                      rgb(250, 230, 145));
-  border: 1px solid rgb(201, 189, 141);
-  border-radius: 3px;
-  height: 25px;
-  margin: 9px 9px 0 9px;
-}
-
-.main-page-banner .managed-prefs-gradient {
-  -webkit-margin-end: 20px;
-  -webkit-margin-start: 0;
-  margin-bottom: 9px;
-}
-
-.managed-prefs-text {
-  background-image: url('chrome://theme/IDR_MANAGED');
-  background-position: 5px center;
-  background-repeat: no-repeat;
-  background-size: 16px;
-  display: block;
-  line-height: 24px;
-  padding-left: 26px;
-}
-
-.managed-prefs-banner.clickable:active .managed-prefs-text {
-  background: -webkit-linear-gradient(rgb(250, 230, 145),
-                                      rgb(255, 242, 183));
-}
-
-#page-container .page.showing-banner {
-  margin-top: 45px;
-}
-
 .page list {
   /* Min height is a multiple of the list item height (32) */
   min-height: 192px;
 }
 
 .option {
   margin-top: 0;
 }
 
 .transparent {
@@ skipping 406 matching lines @@
   background-size: 22px;
 }
 
 html[dir='rtl'] .controlled-setting-bubble-text {
   background-position: right top;
 }
 
 .controlled-setting-bubble-action {
   padding: 0 !important;
 }