Examine source code of fastOpenLinks

{
  "manifest_version": 3,
  "author": "trc",
  "name": "fastOpen",
  "description": "set a list of urls to open in one click",
  "version": "1.0",
  "icons": {
    "48": "img/icon-48.png",
    "64": "img/icon-64.png",
    "128": "img/icon-128.png"
  },
  "action": {
    "default_icon": "img/icon-48.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{6702e5f4-d9cd-4496-b8c6-e959750d690a}"
    }
  }
}