spec/fixtures/sub-frames/frame-with-frame-container-webview.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  This is the root page with a webview
  <webview src="./frame-with-frame-container.html" sandbox nodeIntegrationInSubFrames preload="./preload.js"></webview>
</body>
</html>