In some cases, usually after making customization to various code in a SharePoint masterpage, the scrollbar may disappear on SharePoint sites in Chrome.

To fix, look for the following code:

<body scroll="no" onload="if (typeof(_spBodyOnLoadWrapper) != 'undefined') _spBodyOnLoadWrapper();" class="v4master">
Replace that line with the following line:
<body scroll="no" class="v4master"> <script type="text/javascript">$(document).ready(function() {if (typeof(_spBodyOnLoadWrapper) != 'undefined') {_spBodyOnLoadWrapper();} });</script>

That's it!

Original Source:

Note:  this appears to disable features in the ribbon. Work in progress issue…