frame-test-csp-frame-ancestors-none.html

<html>
  <head>
    <title>TabWithEmbeddedPdf</title>
  </head>
  <body>
    <iframe src="test-csp-frame-ancestors-none.pdf"></iframe>
  </body>
</html>

chromium/chrome/test/data/pdf/frame-test-csp-frame-ancestors-none.html