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chromium/third_party/blink/web_tests/fast/hidpi/static/gesture-scroll-amount.html 

<!DOCTYPE html>
<script src='../../../resources/testharness.js'></script>
<script src='../../../resources/testharnessreport.js'></script>
<script src='../../../resources/gesture-util.js'></script>
<style type="text/css">
    body {
        height: 2000px;
        width: 2000px;
    }
</style>
<script>

promise_test(async () => {
  await smoothScrollWithXY(1, 1, 50, 50, GestureSourceType.MOUSE_INPUT, SPEED_INSTANT);

  await waitFor( () => {
    return Math.round(document.scrollingElement.scrollTop) == 1;
  });
  assert_equals(Math.round(document.scrollingElement.scrollTop), 1);
  assert_equals(Math.round(document.scrollingElement.scrollLeft), 1);

  await smoothScrollWithXY(2, 2, 50, 50, GestureSourceType.MOUSE_INPUT, SPEED_INSTANT);

  await waitFor( () => {
    return Math.round(document.scrollingElement.scrollTop) == 3;
  });
  assert_equals(Math.round(document.scrollingElement.scrollTop), 3);
  assert_equals(Math.round(document.scrollingElement.scrollLeft), 3);
}, "Scrolling in a high dpi settings yeilds in the correct offset");
</script>