[Apps Developer Tool] Show installation warnings as chrome://extensions.

chrome/browser/resources/apps_debugger/css/items.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,
 html {
   color: rgb(48, 57, 66);
   font-family: Ubuntu, Arial, sans-serif;
   height: 100%;
   overflow: hidden;
@@ skipping 313 matching lines @@
   -webkit-margin-end: 2.5em;
   padding-top: 7px;
 }
 
 .extension-list-item a {
   -webkit-margin-end: 0.5em;
   -webkit-margin-start: 0;
   display: inline-block;
 }
 
+.install-warnings {
+  background: pink;
+  border-radius: 3px;
+  margin-top: 5px;
+  padding: 2px 5px;
+}
+
 .install-warnings a {
   -webkit-margin-start: 0;
 }
 
+.install-warnings ul {
+  margin: 0;
+}
+
 .extension-details-summary {
   margin-bottom: 10px;
 }
 
 .extension-details-all div {
   margin: 5px 0;
 }
 
 html[dir='rtl'] .delete-link {
   float: left;
@@ skipping 72 matching lines @@
 }
 
 a {
   color: rgb(17, 85, 204);
   text-decoration: underline;
 }
 
 a:active {
   color: rgb(5, 37, 119);
 }