iframe-with-scrolled-fixed-background.html

<!DOCTYPE html>
<iframe frameborder='0' srcdoc="<!DOCTYPE html>
<style>
  ::-webkit-scrollbar { display: none; }
  body {
    background: url('data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\' width=\'100\' height=\'100\'><rect width=\'100%\' height=\'100%\' fill=\'green\'></rect></svg>') no-repeat fixed;
    min-height: 600px;
    min-width: 600px;
  }
</style>
<script>
  onload = function(e) {
    document.documentElement.scrollTop = 20;
  }
</script>" style="width: 100px; height: 100px;"></iframe>

chromium/third_party/blink/web_tests/paint/frames/iframe-with-scrolled-fixed-background.html