Convert SerialIoHandler to use buffer interfaces for I/O API methods.

device/serial/buffer.h

+// 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.
+
+#ifndef DEVICE_SERIAL_BUFFER_H_
+#define DEVICE_SERIAL_BUFFER_H_
+
+#include "base/basictypes.h"
+
+namespace device {
+
+// A fixed-size read-only buffer. The data-reader should call Done() when it is
+// finished reading bytes from the buffer. Alternatively, the reader can report
+// an error by calling DoneWithError() with the number of bytes read and the
+// error it wishes to report.
+class ReadOnlyBuffer {

[raymes, 2014/08/01 02:25:43]

Maybe just "ReadBuffer" and "WriteBuffer" (since I think the WritableBuffer is
really "write only" as well?)

[Sam McNally, 2014/08/01 06:30:31]

Using ReadBuffer and WriteBuffer gets a bit confusing. You end up with Write()
taking a ReadBuffer and Read() taking a WriteBuffer.

+ public:
+  virtual ~ReadOnlyBuffer();
+  virtual const char* GetData() = 0;
+  virtual uint32_t GetSize() = 0;
+  virtual void Done(uint32_t bytes_read) = 0;
+  virtual void DoneWithError(uint32_t bytes_read, int32_t error) = 0;
+};
+
+// A fixed-size writable buffer. The data-writer should call Done() when it is
+// finished writing bytes to the buffer. Alternatively, the writer can report
+// an error by calling DoneWithError() with the number of bytes written and the
+// error it wishes to report.
+class WritableBuffer {
+ public:
+  virtual ~WritableBuffer();
+  virtual char* GetData() = 0;
+  virtual uint32_t GetSize() = 0;
+  virtual void Done(uint32_t bytes_written) = 0;
+  virtual void DoneWithError(uint32_t bytes_written, int32_t error) = 0;
+};
+
+}  // namespace device
+
+#endif  // DEVICE_SERIAL_BUFFER_H_