Examine source code of MRN Reader

{
  "manifest_version": 2,
  "name": "MRN Reader",
  "version": "1.2",
  "description": "Extracts MRN numbers from EU customs pages. Year and country code auto-detected.",
  "author": "Jürgen Riegg",
  "homepage_url": "https://paypal.me/juergenriegg",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "MRN Reader",
    "default_icon": {
      "16": "icon-16.svg",
      "32": "icon-16.svg",
      "48": "icon-16.svg",
      "128": "icon-16.svg"
    }
  },
  "icons": {
    "16": "icon-16.svg",
    "32": "icon-16.svg",
    "48": "icon-16.svg",
    "128": "icon-16.svg"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "mrn-reader@juergenriegg.de",
      "strict_min_version": "79.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}