Examine source code of Day Count

{
  "manifest_version": 3,
  "name": "Day Count",
  "version": "1.0",
  "description": "Add day count widgets to firefox new tab page",
  "icons": {
    "48": "icons/hironogoldfish.jpg"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "ez-srs.nixos@gmail.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  }
}