Examine source code of todo_newtab_override

{
  "manifest_version": 2,
  "name": "todo_newtab_override",
  "version": "1.0",
  "description": "swaps new tab to a locally-stored page with todo lists. Can export and import this list through json. All data is stored locally in the browser",
  "chrome_url_overrides": {
    "newtab": "./index.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "id": "{b966f3e2-f38b-4bec-bd7e-e5d52894b361}"
    }
  }
}