Examine source code of CustomHomeTab

{
  "manifest_version": 3,
  "name": "about:newtab Customizer",
  "version": "1.0",
  "description": "Customize Firefox's new tab page with various options",
  "browser_specific_settings": {
    "gecko": {
      "id": "newtabcustomizer@mccram12.wow",
      "strict_min_version": "58.0"
    }
  },
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  },
  "permissions": [
    "storage",
    "topSites"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html"
  },
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  }
}