Remove the mojo serial interfaces and related infrastructure.

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;
-
-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);
-};
-
-interface DataSink {
-  // 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. The response contains the number of
-  // bytes successfully sent and an optional error. If |error| is zero,
-  // |bytes_sent| will the size of |data|.
-  OnData(array<uint8> data) => (uint32 bytes_sent, int32 error);
-
-  // Called to clear the error and resume data transmission after an error
-  // occurs. After an error is reported in response to an OnData until
-  // ClearError is called, any further OnData calls will report the same error
-  // as the first error response.
-  ClearError();
-};