chromium/third_party/blink/web_tests/fast/spatial-navigation/snav-simple-content-overflow.html

<!DOCTYPE html>
<!--
    This test ensures that overflowed content can be focused by Spatial Navigation.

    * Pre-conditions:
    1) DRT support for SNav enable/disable.

    * Navigation steps:
    1) Loads this page, focus goes to "start" automatically.
    3) Try to traverse the links on page down.
       and then back up.

    * Expected results: After 'start' gets the focus, tapping down arrow should scroll its
      enclosing scrollable container (<div>) down, and *not* move focus to the link whose id is '2'.
  -->
<style type="text/css">
  div.scroll {
    height: 200px;
    width: 300px;
    overflow: auto;
    border: 1px solid #666;
    background-color: #ccc;
    padding: 8px;
  }
</style>

<div class="scroll">
  <p>It has a visible <a id="start" href="a">link_1</a>.</p>
  <br><br><br><br><br><br><br><br><br>
  <p>... and an overflowed link like <a id="1" href="a">this</a>.</p>
</div>
<br><br><br><br><br><br><br>
<p>This link should NOT get <a id="start" href="a">focused</a>.</p>

<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script src="resources/snav-testharness.js"></script>
<script type="application/javascript">
  var resultMap = [
    ["Down", "start"]
  ];

  // starting the test itself: get to a known place.
  document.getElementById("start").focus();
  snav.assertFocusMoves(resultMap);
</script>