Examine source code of AutoCloseTab

{
  "manifest_version": 2,
  "name": "AutoCloseTab",
  "version": "1.1",
  "description": "Automatically closes tabs with specified URLs.",
  "icons": {
    "48": "icons/border-48.png"
  },
  "permissions": [
    "tabs",
    "webNavigation",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b7887364-c27d-4496-95f6-b246772df01a}"
    }
  }
}