Examine source code of Tab - Close All

{
  "manifest_version": 2,
  "name": "Tab - Close All",
  "description": "Add a tab context menu to close all tabs",
  "version": "1.1resigned1",
  "default_locale": "en",
  "applications": {
    "gecko": {
      "strict_min_version": "61.0",
      "id": "{b19bc22e-c148-4816-9c53-340f587c1a06}"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "menus",
    "activeTab",
    "tabs"
  ]
}