Examine source code of Auto-reduce Tabs

{
  "manifest_version": 2,
  "name": "Auto-reduce Tabs",
  "version": "0.1.1resigned1",
  "description": "Close tabs before getting too many; Forcibly limits the number of tabs. You can change the limit.",
  "applications": {
    "gecko": {
      "id": "@auto-reduce-tabs",
      "strict_min_version": "48.0"
    }
  },
  "icons": {
    "256": "icon.svg"
  },
  "background": {
    "scripts": [
      "boilerplate.js",
      "background.js"
    ]
  },
  "permissions": [
    "storage"
  ],
  "options_ui": {
    "page": "options.html"
  }
}