file_frame_src_frame_governs.html

Enable keyboard shortcuts

<html>

<head>

  <meta charset="utf-8">

  <meta http-equiv="Content-Security-Policy" content="frame-src https://example.com; child-src 'none'">";

</head>

<body>

<iframe id="testframe"></iframe>

<script type="text/javascript" src="file_frame_src.js"></script>

</body>

</html>