Examine source code of Unit.Travel

{
  "browser_specific_settings": {
    "gecko": {
      "id": "info@unit.travel",
      "strict_min_version": "42.0"
    }
  },
  "action": {
    "default_icon": {
      "32": "assets/img/128.png",
      "128": "assets/img/128.png"
    },
    "default_popup": "popup/popup.html",
    "default_title": "Unit travel"
  },
  "background": {
    "scripts": [
      "common/config.js",
      "common/lang.js",
      "api/booking.js",
      "common/install.js"
    ]
  },
  "content_scripts": [
    {
      "js": [
        "vendor/jquery/3.5.1/jquery.min.js",
        "common/config.js",
        "common/lang.js",
        "api/booking.js"
      ],
      "matches": [
        "https://*.booking.com/*",
        "https://*.unit.travel/affiliateprogram/success.html*"
      ],
      "run_at": "document_start"
    },
    {
      "css": [
        "content/booking/content.css"
      ],
      "js": [
        "content/booking.js"
      ],
      "matches": [
        "https://*.booking.com/*"
      ],
      "run_at": "document_idle"
    },
    {
      "css": [
        "content/booking/content.css"
      ],
      "js": [
        "content/unit.js"
      ],
      "matches": [
        "https://*.unit.travel/affiliateprogram/success.html*"
      ],
      "run_at": "document_idle"
    }
  ],
  "default_locale": "ru",
  "description": "__MSG_appDesc__",
  "homepage_url": "https://unit.travel/",
  "icons": {
    "32": "assets/img/128.png",
    "128": "assets/img/128.png"
  },
  "manifest_version": 3,
  "name": "__MSG_appName__",
  "options_ui": {
    "open_in_tab": true,
    "page": "options/options.html"
  },
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "https://*.booking.com/*",
    "https://*.unit.travel/*"
  ],
  "short_name": "__MSG_appName__",
  "version": "1.0.3",
  "web_accessible_resources": [
    {
      "matches": [
        "<all_urls>"
      ],
      "resources": [
        "assets/img/*",
        "content/*"
      ]
    }
  ]
}