Examine source code of Boxel Golf

{
  "action": {
    "default_popup": "index.html",
    "default_title": "Boxel Golf"
  },
  "description": "Boxel Golf is a multiplayer golf game packed with challenging courses, custom hats, and a powerful level builder.",
  "differential_fingerprint": "1.39a9425e8f5f6cb9229b5161c3e6603c4db4cd378d6222e8a0d3b3b6f5fbe06c",
  "icons": {
    "16": "img/png/icon16.png",
    "48": "img/png/icon48.png",
    "128": "img/png/icon128.png"
  },
  "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAi8rxLcga2lLUQG+gVgRAU7OcaFJ7AWs6lNk/MgZHxki9HTbc3G9+evEvmXobUQEgDbj9ohNT5AL7MOkHhr9+eoMhjmtRQSQIvpZOQ7aw4IAMXjVPinNX/Nac98AY5OhzWyhtJ2q+J0PpJ1Y4+cenKZhAIaOpJVhQ/HilujCFY2dIFmRP0SN8mPYw4LaeWBL7kRMdWSpadG5h2TsYa+d7e+bDNTkYDJsUJeZaqSRDn7sNt6w42hiWjX0hH3531Ms2DK9/x5WmPhh1Y0kTQffxgLBan00Mk+YmTsLEn62hO5QpXCZImFbvG1OENN9x7m7f2T1Xl9xu9fXBT04bid+ugQIDAQAB",
  "manifest_version": 2,
  "name": "Boxel Golf",
  "update_url": "https://clients2.google.com/service/update2/crx",
  "version": "1.2.2",
  "browser_specific_settings": {
    "gecko": {
      "id": "{4fbb7b72-4a8d-47df-8c33-fd7837989b5d}"
    }
  }
}