Examine source code of Custom New Tab

{
  "manifest_version": 3,
  "author": "Mohammad Anwar",
  "name": "Custom New Tab",
  "short_name": "CNT",
  "description": "Replace your new tab with a custom URL, solid color, or your own HTML. Lightweight, offline, and private.",
  "offline_enabled": true,
  "version": "1.3.0",
  "icons": {
    "16": "images/icon_16.png",
    "32": "images/icon_32.png",
    "48": "images/icon_48.png",
    "128": "images/icon_128.png"
  },
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  },
  "background": {
    "scripts": [
      "worker.js"
    ]
  },
  "action": {
    "default_title": "Custom New Tab",
    "default_icon": "images/icon_16.png"
  },
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "cnt@anwar.app"
    }
  }
}