Examine source code of Auto_Group

{
  "manifest_version": 2,
  "name": "Auto_Group",
  "version": "1.0",
  "description": "Automaticly make tab groups for webpages of same domain",
  "permissions": [
    "tabs",
    "tabGroups",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "auto_group.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "auto_group@example.com"
    }
  }
}