Change data pipe wrappers used by SerialConnection to use message pipe.

device/serial/data_stream_serialization.mojom

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import "data_stream.mojom"
 
 module device.serial {
 
 // A serialized form of a DataSender.
 struct SerializedDataSender {
   // The control channel to the DataSink to which this DataSender sends data.
   DataSink sink;
 
-  // The data pipe this DataSender uses to send data to the DataSink.
-  handle<data_pipe_producer> data_pipe;
-
   // The error to report for sends in progress when a fatal error occurs.
   int32 fatal_error_value;
+
+  // The size of the send buffer.
+  uint32 buffer_size;
 };
 
 // A pending receive error.
 struct PendingReceiveError {
   // The value of the error.
   int32 error;
 
   // The location of the error.
   uint32 offset;
 };
 
 // A serialized form of a DataReceiver.
 struct SerializedDataReceiver {
   // The control channel to the DataSource from which this DataReceiver receives
   // data.
   DataSource source;
 
-  // The data pipe this DataReceiver uses to receive data from the DataSource.
-  handle<data_pipe_consumer> data_pipe;
-
   // The error to report for a receive in progress when a fatal error occurs.
   int32 fatal_error_value;
 
   // The number of bytes this DataReceiver has received from the DataSource.
   uint32 bytes_received;
 
   // Whether a Resume() message needs to be sent to the DataSource for it to
   // resume sending data.
   bool paused;
 
   // The pending receive error if there is one.
   PendingReceiveError? pending_error;
+
+  array<array<uint8>> pending_data;
 };
 
 }