Merge "Expose TakeXXXFd from UDS's ChannelEventReceiver"

  BorrowedHandle pollhup_event_fd() const { return pollhup_event_fd_.Borrow(); }

  BorrowedHandle data_fd() const { return data_fd_.Borrow(); }

  // Moves file descriptors out of ChannelEventReceiver. Note these operations

  // immediately invalidates the receiver.

  std::tuple<LocalHandle, LocalHandle, LocalHandle> TakeFds() {

    epoll_fd_.Close();

    return {std::move(data_fd_), std::move(pollin_event_fd_),

            std::move(pollhup_event_fd_)};

  }

  Status<int> GetPendingEvents() const;

  Status<int> PollPendingEvents(int timeout_ms) const;