addEngineFromExtension(extension) {
  let metadata = this.metaDataFromManifest(extension.manifest);
  this.addEngineFromMetaData(metadata)
  if extension.isPriviledged {
    if extension.id in lists.json.overrides {
      for overrideLocale in lists.json.overrides[extension.id] {
        localizedManifest = extension.getLocalizedManifest(overrideLocale)
		metadata = this.metaDataFromManifest(localizedManifest);
        this.addEngineFromMetaData(metadata)
      }
    }
  }
}