<html>
<head>
<style>
::-webkit-scrollbar {
    height: 30px;
    width: 30px;
}

::-webkit-scrollbar-thumb {
    background-color: blue;
    height: 30px;
    width: 30px;
}

body {
  background-color: black;
}

</style>
<script>
function test()
{
    if (window.testRunner) {
        testRunner.waitUntilDone();
        testRunner.dumpAsText(true);
        testRunner.displayAndTrackRepaints();
    }

    window.setTimeout(function() {
        document.scrollingElement.scrollTop = 2000;
        if (window.testRunner) {
            testRunner.displayAndTrackRepaints();
            testRunner.notifyDone();
        }
    }, 0);
}
</script>
</head>
<body onload="test()">
<div style="height: 2000px; color: white;">PASS if blue scrollbar is at the bottom.</div>
</body>
</head>