secure_connection_start_zero_on_localhost.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <title>secureConnectionStart on non-https localhost</title>
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
  </head>
  <body>
    <script>
      window.onload = () => {
          test(t => {
              const entry = performance.getEntriesByType("navigation")[0];
              assert_equals(entry.secureConnectionStart, 0, "secureConnectionStart is non-zero");
          }, "Test that secureConnectionStart is zero");
      };
    </script>
  </body>
</html>

chromium/third_party/blink/web_tests/http/tests/navigation-timing/secure_connection_start_zero_on_localhost.html