<!DOCTYPE html>
<head>
<title>A below-viewport loading=lazy image in a cross origin iframe loads only
       when scrolled into viewport</title>
<link rel="help" href="https://html.spec.whatwg.org/multipage/urls-and-fetching.html#lazy-loading-attributes">
<link rel="author" title="Dom Farolino" href="mailto:dom@chromium.org">
<link rel="author" title="Rob Buis" href="mailto:rbuis@igalia.com">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/common/get-host-info.sub.js"></script>
</head>

<iframe id="iframe" width="500px" height="500px"></iframe>

<script>
promise_test(t => {
  iframe.src =
    get_host_info().HTTP_NOTSAMESITE_ORIGIN +
    new URL("resources/", self.location).pathname +
    "image-loading-lazy-below-viewport.html";

  // Wait for the frame to report that its window load event fired.
  return new Promise(resolve => {
    window.addEventListener("message",
                            event => resolve(event.data), {once: true});
  }).then(iframe_message => {
    assert_equals(iframe_message, "window_loaded",
                  "The loading=lazy image should not block the iframe's load " +
                  "event");

    // Tell the iframe to scroll the image element into view.
    frames[0].postMessage("scroll", "*");

    return new Promise(resolve => {
      window.addEventListener("message", event => resolve(event.data));
    });
  }).then(iframe_message => {
    assert_equals(iframe_message, "image_loaded",
                  "The below-viewport loading=lazy image should load only " +
                  "once scrolled into the viewport");

  }); // new Promise();
}); // promise_test.
</script>
