Added documentation for In-App Payments API.

chrome/common/extensions/docs/static/css/site.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.
  */
 
 .hidden {
   display: none;
 }
 
 body {
@@ skipping 548 matching lines @@
 
 .imaged li img {
   float: right;
   margin-bottom: 1em;
 }
 
 .imaged + p {
   clear: right;
 }
 
+/* small indent for better visual distinction
+   (e.g., in a long list) */
+.indent-small {
+  margin-left: 2em;
+}
+
 /* Tabbed pane with header (tabs) and content */
 tabs {
   margin: 25px 0;
   display: block;
 }
 tabs header {
   display: inline-block;
   padding: 10px;
   border: 1px solid #ccc;
   margin-bottom: 0;
@@ skipping 12 matching lines @@
   border: 1px solid #ccc;
   margin-top: -1px;
 }
 tabs content.unselected {
   display: none;
 }
 tabs content pre {
   margin: 0;
   padding: 10px;
 }