Examine source code of Webpage Archiver

{
  "manifest_version": 2,
  "name": "Webpage Archiver",
  "version": "1.0",
  "description": "Save a complete copy of webpages for offline viewing.",
  "permissions": [
    "activeTab",
    "downloads"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon.png"
  },
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{18116ea1-1099-4809-8b67-11a9e592f02b}"
    }
  }
}