code: func (d *driver) PutContent(context context.Context, path string, contents []byte) error {
  	return retry(func() error {
  		wc := storage.NewWriter(d.context(context), d.bucket, d.pathToKey(path))
  		wc.ContentType = "application/octet-stream"
  		return putContentsClose(wc, contents)
  	})
  }
docs: // PutContent stores the []byte content at a location designated by "path".
  // This should primarily be used for small objects.