Examine source code of Tabs Limiter Extension

{
  "manifest_version": 3,
  "name": "Tabs Limiter Extension",
  "version": "1.0",
  "description": "Limits the number of open tabs.",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "background": {
    "page": "background.html"
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon-16.png",
      "48": "images/icon-48.png",
      "128": "images/icon-128.png"
    }
  },
  "icons": {
    "16": "images/icon-16.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "lucase.mori@gmail.com"
    }
  }
}