chromium/chrome/test/data/load_image/preload_scanner_image.html

<html>
<head></head>
<div>
  This page has an image below the viewport that will only load when it is scrolled into view.
</div>
<div style="height:11000px;"></div>
<img src="image.png" />
<script src="common.js"></script>
<script>
function loadBelowViewportImage() {
  document.images[0].scrollIntoView();
}
</script>
</html>