validation-bubble-device-emulation.html

<!DOCTYPE html>
<p>Check if a validation bubble is shown at a correct position in correct scale
   with device emulation.</p>
<input pattern="\d{4}" title="Please specify four digits." value="abc"
       style="position:absolute; top: 100px; left: 50px;">
<script>
if (window.internals)
  internals.setDeviceEmulationScale(2);
document.querySelector('input').reportValidity();
</script>

chromium/third_party/blink/web_tests/fast/forms/validation-bubble-device-emulation.html