Examine source code of PDF Keyword Crawler

{
  "manifest_version": 3,
  "name": "PDF Keyword Crawler",
  "version": "3.0.3",
  "description": "Busca un keyword en PDFs remotos listados en un archivo.",
  "permissions": [
    "tabs"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "action": {
    "default_title": "Abrir herramienta"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    {
      "resources": [
        "pdf.worker.js"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "pdf-keyword-crawler@ak1t4"
    }
  }
}