chromium/third_party/blink/manual_tests/fullscreen/full-screen-flash.html

<style>
    body { background: green; color: white; }
    body:-webkit-full-screen-ancestor { background: red; }
    span { text-decoration: underline; cursor: hand; }
    div {
        background: blue;
        width: 200px;
        height: 100px;
    }
    div:-webkit-full-screen {
        width: 100%;
        height: 100%;
    }
</style>
<script>
function toggleFullScreen() {
    if (document.webkitIsFullScreen)
        document.webkitCancelFullScreen();
    else
        document.getElementsByTagName('div')[0].webkitRequestFullscreen();
}
</script>
<body>
    This tests that the page does not have a visible "flash" when finishing the exit full screen animation.
    <span onclick="toggleFullScreen()">Click to toggle full screen.</span>
    <div>
    </div>
</body>