chromium/third_party/blink/web_tests/fast/media/resources/media-query-list-callback-frame.html

<!DOCTYPE html>
<style>
@media (max-width: 200px) {
  body {
    background: orange;
  }
}
</style>
<script>
var mql = window.matchMedia('(max-width: 200px)');
mql.addListener(function (mql) {
});
</script>