<!DOCTYPE html>
<script>
    if (window.testRunner) {
        testRunner.dumpAsText();
        testRunner.dumpChildFrames();
        testRunner.waitUntilDone();
    }
    if (window.internals) {
        internals.settings.setLogDnsPrefetchAndPreconnect(true);
    }
</script>
This test checks if a Link header inside an iframe triggered a dns prefetch.
<iframe src="resources/link-dnsprefetch-frame.php"></iframe>