Examine source code of bergfex OnlyMap

{
  "manifest_version": 3,
  "name": "bergfex OnlyMap",
  "description": "Show bergfex map in full screen.",
  "version": "0.6",
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://www.bergfex.at/*",
        "*://www.bergfex.ch/*",
        "*://www.bergfex.de/*",
        "*://www.bergfex.it/*",
        "*://www.bergfex.fr/*",
        "*://www.bergfex.sk/*",
        "*://www.bergfex.pl/*",
        "*://www.bergfex.si/*",
        "*://www.bergfex.es/*",
        "*://www.bergfex.cz/*",
        "*://*.bergfex.com/*",
        "*://www.bergfex.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "action": {
    "default_icon": "icons/icon.png"
  },
  "icons": {
    "250": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "bergfexOnlyMap@guerrillamail.org"
    }
  }
}