chromium/third_party/blink/web_tests/external/wpt/client-hints/viewport-size/viewport-size-subresource.https.html

<!DOCTYPE html>
<html>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
promise_test(t => {
  return new Promise(resolve => {
    window.addEventListener("message", t.step_func(e => {
      assert_equals(e.data, "503,614");
      resolve();
    }));
  });
});
</script>
<iframe src="../resources/viewport-measurement.html" width=503 height=614>