Revert of Remove Client= from device/serial/data_stream.mojom.

device/serial/data_stream.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.
 
 module device.serial;
 
+[Client=DataSourceClient]
 interface DataSource {
   // Initializes this DataSource with the amount of data its client will
   // buffer.
   Init(uint32 buffer_size);
 
   // Resumes sending data after it has been stopped due to an error.
   Resume();
 
   // Reports that |bytes_sent| bytes have been successfully passed to the
   // client.
   ReportBytesReceived(uint32 bytes_sent);
 };
 
 interface DataSourceClient {
   // Invoked to report |error| from the DataSource. No further bytes will be
   // transmitted from the DataSource until Resume() is called.
   OnError(int32 error);
 
   // Invoked to transmit data from the DataSource.
   OnData(array<uint8> data);
 };
 
+[Client=DataSinkClient]
 interface DataSink {
   // Initializes this DataSink with the amount of data it is expected to
   // buffer.
   Init(uint32 buffer_size);
 
   // Requests the cancellation of any data that has been written to the pipe,
   // but has not yet been sent to the sink.
   Cancel(int32 error);
 
   // Invoked to pass |data| to the sink.
   OnData(array<uint8> data);
 };
 
 interface DataSinkClient {
   // Reports that the sink has successfully received |bytes_sent| bytes of data.
   ReportBytesSent(uint32 bytes_sent);
 
   // Reports that the sink has received |bytes_sent| bytes of data (possibly 0)
   // and encountered an error: |error|. Any OnData messages received by the
   // DataSink before the response will be discarded. The client should respond
   // when it is ready to resume sending data.
   ReportBytesSentAndError(uint32 bytes_sent, int32 error) => ();
 };