chromium/third_party/blink/web_tests/wpt_internal/printing/scaling-002-print.html

<!DOCTYPE html>
<link rel="match" href="scaling-002-print-ref.html">
<script>
  if (window.testRunner) {
    testRunner.setPrintingScaleFactor(0.5);
  }
</script>
<style>
  body {
    margin: 0;
  }
</style>
<div style="height:100vh; background:yellow;">
  This page should be all yellow.
</div>
<div style="height:100vh; background:orange;">
  This page should be all orange.
</div>