Examine source code of Editable Empty New Tab

{
  "manifest_version": 3,
  "name": "Editable Empty New Tab",
  "version": "1.0.4",
  "description": "Override browser's new tab page with an empty (but editable) tab",
  "homepage_url": "https://github.com/liskin/empty-tab",
  "icons": {
    "128": "icons/icon128.png"
  },
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "chrome_settings_overrides": {
    "homepage": "index.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{bb4fb93d-d860-4041-b9f2-3727df7a001e}"
    }
  }
}