Adds functionality to pack an extension / app from the app.

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 {
   overflow: visible;
 }
 
 /* Contents */
@@ skipping 123 matching lines @@
 
 .extension-list-item a {
   -webkit-margin-start: 0.5em;
   display: inline-block;
 }
 
 .install-warnings a {
   -webkit-margin-start: 0;
 }
 
+/* Overlays */
+
+#overlay {
+  z-index: 5;
+}
+
+#overlay .page:not(.showing) {
+  display: none;
+}
+
 /* Trash */
 
 #extension-settings .trash {
   -webkit-transition: opacity 200ms;
   height: 22px;
   opacity: 0.8;
   position: absolute;
   right: 0;
   top: 3px;
   vertical-align: middle;
@@ skipping 17 matching lines @@
 }
 
 a {
   color: rgb(17, 85, 204);
   text-decoration: underline;
 }
 
 a:active {
   color: rgb(5, 37, 119);
 }