chromium/third_party/blink/web_tests/fast/media/mq-max-pixel-ratio.html

<html>
<head>
<title>CSS3 media query test: Device-pixel ratio query. Using style element, @media css rule.</title>
<style type="text/css">
@media  screen and (-webkit-max-device-pixel-ratio: 1.5) {
    p { color:green; }
}

</style>
</head>

<body>
<p>This text should be green if the resolution scaling factor is 1.5 or smaller. Otherwise, it should be black.</p>
</body>
</html>