Examine source code of Bookmark Updater

{
  "manifest_version": 3,
  "name": "Bookmark Updater",
  "description": "Update URL for bookmark with the same as added bookmark name and remove all doubles.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{35b04263-bef7-4d01-86c0-8209552edb5f}"
    }
  },
  "permissions": [
    "bookmarks"
  ],
  "version": "0.2",
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}