Examine source code of Offline Reading Saver

{
  "manifest_version": 2,
  "name": "Offline Reading Saver",
  "version": "1.0",
  "description": "Save content for offline reading.",
  "permissions": [
    "downloads",
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_title": "Save Page Offline",
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{01b4aa25-2642-4ac5-8076-1235e38e6234}"
    }
  }
}