scrollbar-appearance-increase-device-scale-factor.html

<!DOCTYPE html>
<script>
  function finishTest() {
    testRunner.notifyDone();
  }
  function scaleUp() {
    testRunner.setBackingScaleFactor(3, finishTest);
  }
  function startTest() {
    testRunner.waitUntilDone();
    setTimeout(scaleUp, 1);
  }
  if (window.testRunner) {
    onload = startTest;
  }
</script>
<div id="div" style="width:200px; height:120px; overflow:auto">
  <br>This should be a scrollable text box with horizontal and vertical scroll.
  <div style="width:400px; height: 200px"></div>
</div>

chromium/third_party/blink/web_tests/fast/hidpi/scrollbar-appearance-increase-device-scale-factor.html