preload/link_header_preload_delay_onload.html

<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
    var t = async_test('Makes sure that Link headers preload resources and block window.onload after resource discovery');
</script>
<body>
<style>
    #background {
        width: 200px;
        height: 200px;
        background-image: url(resources/square.png?background);
    }
</style>
<link rel="stylesheet" href="resources/dummy.css">
<script src="resources/dummy.js"></script>
<div id="background"></div>
<script>
    document.write('<img src="resources/square.png">');
    window.addEventListener("load", t.step_func(function() {
        var entries = performance.getEntriesByType("resource");
        var found_background_first = false;
        for (var i = 0; i < entries.length; ++i) {
            var entry = entries[i];
            if (entry.name.indexOf("square") != -1) {
                if (entry.name.indexOf("background") != -1)
                    found_background_first = true;
            }
        }
        assert_true(found_background_first);
        assert_equals(entries.length, 6);
        t.done();
    }));
</script>