Warn user in case extension delays network traffic too much.

chrome/browser/resources/options/extension_settings.css

 /*
 Copyright (c) 2011 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.
 */
 
 .details-view {
   -webkit-padding-end: 10px;
 }
 
@@ skipping 120 matching lines @@
 .extension-links-trailing {
   -webkit-padding-end: 7px;
 }
 
 .extension-zippy-container {
   cursor: pointer;
   width: 20px;
   -webkit-user-select: none;
 }
 
+.extension-warning-title {
+  color: red;
+}
+
+.extension-warnings {
+  margin-top: 6px;
+}
+
+.extension-warnings ul {
+  margin: 0;
+}
+
+.extension-warnings > * {
+  white-space: normal;
+}
+
 .informative-text {
   color: gray;
 }
 
 .extension-zippy-default {
   background-image: url('zippy.png');
   background-repeat: no-repeat;
   background-position: center top;
   position: absolute;
   left: 12px;
@@ skipping 90 matching lines @@
 
 #get-more-extensions-container {
   display: -webkit-box;
 }
 
 #get-more-extensions {
   padding-top: 5px;
   font-size: 15px;
   -webkit-padding-start: 10px;
 }