Examine source code of Quick Checklist

{
  "manifest_version": 2,
  "name": "Quick Checklist",
  "version": "1.0",
  "description": "A minimal checklist right in your toolbar. Add tasks, check them off, done.",
  "browser_specific_settings": {
    "gecko": {
      "id": "quick-checklist@example.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icon-48.png",
      "96": "icon-96.png"
    }
  },
  "permissions": [
    "storage"
  ],
  "icons": {
    "48": "icon-48.png",
    "96": "icon-96.png"
  }
}