code: func (u *ConcurrentUploader) UploadBytes(name string, b []byte, ps *isolatedclient.PushState, done func()) {
  	u.wg.Add(1)
  	go u.upload(name, byteSource(b), ps, done)
  }
docs: // UploadBytes uploads an item held in-memory. UploadBytes does not block. If
  // not-nil, the done func will be invoked on upload completion (both success
  // and failure). The provided byte slice b must not be modified until the
  // upload is completed.
  // TODO(djd): Consider using Upload directly and deleting UploadBytes.