Examine source code of VPN URL Checker

{
  "manifest_version": 2,
  "name": "VPN URL Checker",
  "version": "1.1",
  "description": "Checks if VPN is connected when accessing certain URLs.",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "activeTab",
    "tabs",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "options.html",
    "default_title": "VPN URL Checker"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "icons": {
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "web_accessible_resources": [
    "warning.html"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{6d8178e1-a0ca-416c-b8b8-331674611e47}"
    }
  }
}