Examine source code of ScreenZen Blocker

{
  "manifest_version": 2,
  "name": "ScreenZen Blocker",
  "version": "1.8",
  "description": "*** ScreenZen macOS App Required *** This Firefox extension is a companion to the ScreenZen macOS application and cannot be used independently. Download the ScreenZen app from the macOS App Store first, then install this extension to enable website blocking in Firefox.",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "nativeMessaging",
    "tabs",
    "activeTab",
    "<all_urls>"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; font-src 'self' https://fonts.gstatic.com;",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "web_accessible_resources": [
    "block.html",
    "css/*",
    "js/*",
    "img/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{20b27300-43d7-42c1-b176-ec4a7cd44c05}"
    }
  }
}