message: op-node: Add ChannelOut.InputBytes
diff: @@ -98,6 +98,11 @@ func (co *ChannelOut) AddBlock(block *types.Block) (uint64, error) {
  return uint64(written), err
  }
  +// InputBytes returns the total amount of RLP-encoded input bytes.
  +func (co *ChannelOut) InputBytes() int {
  + return co.rlpLength
  +}
  +
  // ReadyBytes returns the number of bytes that the channel out can immediately output into a frame.
  // Use `Flush` or `Close` to move data from the compression buffer into the ready buffer if more bytes
  // are needed. Add blocks may add to the ready buffer, but it is not guaranteed due to the compression stage.
  @@ -154,7 +159,7 @@ func (co *ChannelOut) OutputFrame(w *bytes.Buffer, maxSize uint64) (uint16, erro
  }
  co.frame += 1
  - fn := uint16(f.FrameNumber)
  + fn := f.FrameNumber
  if f.IsLast {
  return fn, io.EOF
  } else {
  