Examine source code of Country by IP Flags

{
  "manifest_version": 2,
  "name": "Country by IP Flags",
  "version": "1.0",
  "description": "Show country flags near IP addresses on web pages.",
  "minimum_firefox_version": "90.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "{cd55d325-0522-456c-920b-b783b9a5feb8}"
    }
  },
  "permissions": [
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "64": "img/64.png",
    "128": "img/128.png"
  }
}