chromium/third_party/blink/web_tests/http/tests/security/mixedContent/blob-url-in-iframe.html

<!DOCTYPE html>
<html>
<body>
<iframe></iframe>
<p>
  This tests that blob URLs created in a secure context are treated as secure
  origins. This test passes if the iframe renders PASS correctly, and no
  console warning appears.
</p>

<script>
if (window.testRunner) {
    testRunner.dumpAsText();
    testRunner.dumpChildFrames();
    testRunner.waitUntilDone();
}

if (location.protocol != 'https:') {
    location = 'https://127.0.0.1:8443/security/mixedContent/blob-url-in-iframe.html';
} else {
    var iframe = document.querySelector('iframe');
    iframe.onload = function () {
        if (window.testRunner)
            testRunner.notifyDone();
    };

    var b = new Blob(['<h1>PASS (1/1)</h1>'], { type: 'text/html' });
    iframe.src = URL.createObjectURL(b);
}
</script>
</body>
</html>