Examine source code of QR TXT URL

{
  "manifest_version": 2,
  "name": "QR TXT URL",
  "version": "1.1",
  "description": "Los códigos QR no caducan. La extensión permite generar fácilmente códigos QR",
  "browser_action": {
    "default_popup": "index.html"
  },
  "icons": {
    "1000": "img/qr.png"
  },
  "applications": {
    "gecko": {
      "id": "Tatami11@proton.me"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.mozilla.org/*"
      ],
      "js": [
        "script.js"
      ]
    }
  ]
}