Improve layout for bookmark-apps. Add a treatment for small icons.

chrome/browser/resources/ntp4/apps_page.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.
  */
 
 .app {
   position: absolute;
   text-align: center;
 }
 
 .app span {
   display: block;
   text-decoration: none;
   text-overflow: ellipsis;
   white-space: nowrap;
   overflow: hidden;
 }
 
 /* TODO(estade): hover effect? press effect? */
 .app img {
   cursor: pointer;
   display: block;
   margin-left: auto;
   margin-right: auto;
   /* -webkit-mask-image set by JavaScript to the image source */
   -webkit-mask-size: 100% 100%;
 }
 
+.app-icon-div {
+  border: 1px solid gray;
+  border-radius: 4px;
+  cursor: pointer;
+  display: -webkit-box;
+  vertical-align: middle;
+  -webkit-box-align: center;
+}
+
 .app-context-menu > button:first-child {
   font-weight: bold;
 }
 
 .app-context-menu {
   z-index: 1000;
 }
 
 /* Link (bookmark) tiles. */
 .link {
   display: -webkit-box;
   position: absolute;
   -webkit-box-orient: vertical;
 }
 
 .link > * {
   -webkit-box-flex: 1;
 }
 
 .link span {
   display: block;
 }