chromium/chrome/test/data/extensions/api_test/content_scripts/coep_frame/manifest.json

{
  "name": "Load an iframe from content script",
  "version": "0.1",
  "manifest_version": 2,
  "description": "Web accessible resource can be loaded as an iframe in a COEP frame.",
  "permissions": ["https://*/*"],
  "content_scripts": [
    {
      "matches": ["https://*/hello.html"],
      "js": ["content-script.js"]
    }
  ],
  "web_accessible_resources": [
    "iframe.html",
    "script.js"
  ]
}