timer-throttling-out-of-view-cross-origin-page.html

<!DOCTYPE html>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<style>
#frame {
  position: absolute;
  top: -1000px;
}
</style>

<iframe id="frame" sandbox="allow-scripts" src="resources/timer-throttling-frame.html"></iframe>

<script>
if (window.testRunner)
  testRunner.dumpAsText();
let throttlingTest = async_test("Test timer throttling in out-of-view cross origin frames");

var frame = document.querySelector('#frame');
frame.addEventListener('load', () => {
  // Throttling only happens after the first layout, so start the test after
  // that.
  requestAnimationFrame(() => {
    frame.contentWindow.postMessage(null, '*');
  });
});

addEventListener('message', (e) => {
  let timerDelay = e.data;
  throttlingTest.step(() => {
    assert_greater_than(timerDelay, 900, "Timer interval")
  });
  throttlingTest.done();
});
</script>

chromium/third_party/blink/web_tests/fast/dom/timer-throttling-out-of-view-cross-origin-page.html