Examine source code of New Tab URL

{
  "manifest_version": 2,
  "name": "New Tab URL",
  "description": "Override the default new tab with a specified URL",
  "version": "1.2.1",
  "icons": {
    "64": "assets/icons/icon.svg"
  },
  "chrome_url_overrides": {
    "newtab": "new-tab/index.html"
  },
  "options_ui": {
    "page": "options/index.html"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "@new-tab-url",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}