Examine source code of Search in this site

{
  "manifest_version": 3,
  "name": "Search in Site",
  "version": "1.0.0",
  "description": "Search within the current site using the site: operator",
  "icons": {
    "16": "icons/icon.svg",
    "32": "icons/icon.svg",
    "48": "icons/icon.svg",
    "96": "icons/icon.svg"
  },
  "action": {
    "default_title": "Search in this site",
    "default_icon": "icons/icon.svg"
  },
  "permissions": [
    "contextMenus",
    "activeTab",
    "storage"
  ],
  "commands": {
    "open-popup": {
      "suggested_key": {
        "default": "Ctrl+Shift+L"
      },
      "description": "Open search popup for the current site"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "searchinsite@plucafs",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}