scrollbar-damage-and-full-viewport-repaint.html

<!DOCTYPE html>
<style>
/* To ensure full viewport repaint when viewport is resized. */
body {
    background-image: linear-gradient(red, blue);
    background-attachment: fixed;
    margin: 0;
}
#container {
    width: 200px;
    height: 200px;
    border: 1px solid black;
    overflow: scroll;
}
#child {
    width: 100px;
    height: 100px;
}
</style>
<script src="../resources/text-based-repaint.js" type="text/javascript"></script>
<script>
function repaintTest() {
    // Invalidation of horizontal scrollbar should be tracked.
    document.getElementById('child').style.width = '2000px';
}
window.onload = async function() {
    // Trigger a full viewport repaint to test if scrollbar damages are cleared
    // even if we shortcut children invalidations.
    var resizePromise = new Promise(resolve => window.onresize = resolve);
    window.resizeTo(1000, 600);
    await resizePromise;
    // Invalidation of vertical scrollbar before the repaint test should not be tracked during repaintTest().
    document.getElementById('child').style.height = '2000px';
    runRepaintAndPixelTest();
};
</script>
<div style="height: 50px">
Tests if scrollbar damage flag is cleared during a full viewport invalidation.
Passes if the result repaint rects contain the horizontal scrollbar but not the vertical scrollbar.
</div>
<div id="container">
    <div id="child"></div>
</div>

chromium/third_party/blink/web_tests/paint/invalidation/scroll/scrollbar-damage-and-full-viewport-repaint.html