Examine source code of CreaSign

{
  "manifest_version": 2,
  "name": "CreaSign",
  "description": "CreaSign - Digital Signature Component",
  "version": "1.0",
  "author": "CREA d.o.o.",
  "homepage_url": "http://www.crea.si",
  "icons": {
    "128": "icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "contentscript.js"
      ],
      "all_frames": true,
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "nativeMessaging"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "creasign.ff@crea.si",
      "strict_min_version": "67.0"
    }
  }
}