Examine source code of Sign Connect

{
  "manifest_version": 2,
  "name": "Sign Connect",
  "description": "Sign Connect is required to digitally sign with USB Tokens connected to your computer directly from your browser",
  "version": "1.0.2",
  "icons": {
    "32": "images/icon-32.png",
    "64": "images/icon-64.png",
    "96": "images/icon-96.png",
    "128": "images/icon-128.png",
    "256": "images/icon-256.png",
    "512": "images/icon-512.png"
  },
  "background": {
    "scripts": [
      "service_worker.js"
    ]
  },
  "content_scripts": [
    {
      "js": [
        "content_script.js"
      ],
      "matches": [
        "https://*/*",
        "http://*/*"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "https://*/*",
    "http://*/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{00ba624a-be8d-47d0-a24d-885814016287}"
    }
  }
}