chrome/test/data/beforeunload.html - chromium/src - Git at Google

 <html>
   <head>
     <title>Loading...</title>
   </head>
   <body onload="attachUnloadListener()">
     <script>
       window.onbeforeunload = function(e) { return 'foo'; };
     </script>
     <p>Navigate to another page to trigger beforeunload handler.</p>
   </body>
 </html>
	<html>
	<head>
	<title>Loading...</title>
	</head>
	<body onload="attachUnloadListener()">
	<script>
	window.onbeforeunload = function(e) { return 'foo'; };
	</script>
	<p>Navigate to another page to trigger beforeunload handler.</p>
	</body>
	</html>