Examine source code of Private Tab Exporter

{
  "manifest_version": 2,
  "name": "Private Tab Exporter",
  "version": "1.0",
  "description": "Export URLs from private tabs automatically",
  "permissions": [
    "tabs",
    "downloads"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "incognito": "spanning",
  "browser_action": {
    "default_title": "Export Tabs"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ef99e1e0-c240-4e70-a86f-94371624b25a}"
    }
  }
}