func WriteGoogleAssets(encoder Encoder, opts *AssetOpts, bucket string, cred string, volumeSize int) error {
	if err := WriteAssets(encoder, opts, googleBackend, googleBackend, volumeSize, ""); err != nil {
		return err
	}
	return WriteSecret(encoder, GoogleSecret(bucket, cred), opts)
}
func WriteGoogleAssets(encoder Encoder, opts *AssetOpts, bucket string, cred string, volumeSize int) error {
	if err := WriteAssets(encoder, opts, googleBackend, googleBackend, volumeSize, ""); err != nil {
		return err
	}
	return WriteSecret(encoder, GoogleSecret(bucket, cred), opts)
}
// WriteGoogleAssets writes assets to a google backend.