Examine source code of Booking Optimizer

{
  "name": "Booking Optimizer",
  "description": "Auto-apply filters when doing research on Booking.com",
  "version": "1.0.0",
  "manifest_version": 2,
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Open the popup"
  },
  "optional_permissions": [
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://www.booking.com/searchresults*"
      ],
      "run_at": "document_end",
      "js": [
        "./index.global.js"
      ]
    }
  ],
  "background": {
    "page": "background.html",
    "persistent": false
  },
  "permissions": [
    "storage"
  ],
  "icons": {
    "128": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b5542b47-e464-4f48-bd17-fc026649ff06}"
    }
  }
}