Show alert failure for reloading unpacked extensions with bad manifest

chrome/browser/resources/extensions/extension_load_error.css

 /* Copyright 2014 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. */
 
 #extension-load-error {
   -webkit-margin-before: 10px;
   -webkit-margin-end: 20px;
   -webkit-padding-after: 10px;
   -webkit-padding-end: 3px;
   -webkit-padding-start: 10px;
@@ skipping 20 matching lines @@
   max-height: 100px;
 }
 
 #extension-load-error-manifest .extension-code-highlighted-source {
   background-color: pink;
 }
 
 #extension-load-error-controls {
   align-self: flex-end;
 }
+
+#extension-load-error-additional > span {
+  font-size: 12px;
+  font-weight: bold;
+}
+
+#extension-load-error-additional > li {
+  -webkit-margin-after: 0;
+  -webkit-margin-before: 3px;
+}