chromium/third_party/blink/web_tests/accessibility/image-loaded-events.html

<!DOCTYPE html>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>

<img id="img">

<script>
async_test(function(t) {
    var img = document.getElementById("img");
    var axImg = accessibilityController.accessibleElementById("img");
    axImg.addNotificationListener((notification) => {
        if (notification == "MarkDirty")
            t.done();
    });
    img.src = "resources/cake.png";
}, "A notification is received when an image is loaded on an img element.");
</script>