<!DOCTYPE html>
<head>
  <title>In-viewport loading=lazy iframes do not block the window load event</title>
  <link rel="author" title="Dom Farolino" href="mailto:dom@chromium.org">
  <script src="/resources/testharness.js"></script>
  <script src="/resources/testharnessreport.js"></script>
  <script src="../resources/common.js"></script>
</head>

<body>
  <!-- This image blocks the window load event for 1 second -->
  <img src="/common/square.png?pipe=trickle(d1)">

  <!-- These iframes must load because they intersect the viewport, but they must
       not block the window load event, because they are loading=lazy -->
  <iframe id="visible" loading="lazy"
       src="resources/subframe.html?visible&pipe=trickle(d3)"></iframe>
  <iframe id="visibility_hidden" style="visibility:hidden;" loading="lazy"
       src="resources/subframe.html?visibility_hidden&pipe=trickle(d3)"></iframe>
</body>

<script>
  const visible_iframe = document.querySelector('#visible');
  const hidden_iframe = document.querySelector('#visibility_hidden');

  const visible_iframe_t =
    async_test('In-viewport loading=lazy iframe does not block the load event');

  const hidden_iframe_t =
    async_test('In-viewport loading=lazy visibility:hidden iframe does not ' +
               'block the load event');

  let has_window_loaded = false;
  window.addEventListener("load", () => {
    has_window_loaded = true;
  });

  visible_iframe.onload = visible_iframe_t.step_func_done(() => {
    assert_true(has_window_loaded,
                "The visible iframe should not block the load event");
  });

  hidden_iframe.onload = hidden_iframe_t.step_func_done(() => {
    assert_true(has_window_loaded,
                "The hidden iframe should not block the load event");
  });
</script>
