Examine source code of Joomla Counter Control

{
  "manifest_version": 2,
  "name": "Joomla Counter Control",
  "version": "1.3.7",
  "description": "Joomla Counter Control",
  "icons": {
    "64": "icons/icon.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "tabs",
    "cookies",
    "<all_urls>"
  ],
  "options_ui": {
    "page": "options/options.html"
  },
  "browser_action": {
    "default_icon": "icons/icon.png",
    "default_title": "Joomla Counter Control",
    "default_popup": "actions/index.html"
  },
  "applications": {
    "gecko": {
      "id": "joomlacounter@yandex.ru",
      "strict_min_version": "57.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.metg.ru/*",
        "*://www.medregion.ru/*",
        "*://www.mpzu.ru/*",
        "*://sc.medregion.ru/*",
        "*://www.mpzu.ru/*",
        "*://www.uralcom66.ru/*",
        "*://центрпрививок.рф/*",
        "*://privivka74.ru/*"
      ],
      "js": [
        "mrcountercustom.js"
      ]
    }
  ]
}