Examine source code of TimeZone for WhatsApp

{
  "manifest_version": 3,
  "name": "TimeZone for WhatsApp",
  "version": "1.0.0",
  "description": "Shows contact's country, flag, and local time in WhatsApp Web — perfect for international messaging.",
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "https://web.whatsapp.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "timezone-for-whatsapp@extension",
      "strict_min_version": "128.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://web.whatsapp.com/*"
      ],
      "js": [
        "data/countries.js",
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "action": {
    "default_popup": "popup/popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  }
}