Examine source code of YouTube Playlist Timer

{
  "manifest_version": 3,
  "name": "YouTube Playlist Timer",
  "version": "1.3",
  "description": "Affiche le temps total d'une playlist YouTube",
  "browser_specific_settings": {
    "gecko": {
      "id": "youtube-playlist-timer@local",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "icon.png"
  }
}