chromium/chrome/browser/resources/default_apps/external_extensions.json

// Dictionary of default apps to install into new profiles. They will be
// dynamically downloaded and installed from CWS on profile creation.
{
  // Drive extension
  "ghbmnnjooekpmoecnnnilnnbdlolhkhi" : {
    "external_update_url": "https://clients2.google.com/service/update2/crx"
  }
}