Add data pipe wrappers to be used to implement serial receive.

device/serial/data_receiver.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_DATA_RECEIVER_H_
+#define DEVICE_SERIAL_DATA_RECEIVER_H_
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "device/serial/buffer.h"
+#include "device/serial/data_stream.mojom.h"
+#include "mojo/public/cpp/system/data_pipe.h"
+
+namespace device {
+
+class AsyncWaiter;
+
+// A DataReceiver receives data from a DataSource.
+class DataReceiver : public base::RefCounted<DataReceiver>,
+                     public serial::DataSourceClient,
+                     public mojo::ErrorHandler {
+ public:
+  typedef base::Callback<void(scoped_ptr<ReadOnlyBuffer>)> ReceiveDataCallback;
+  typedef base::Callback<void(int32_t error)> ReceiveErrorCallback;
+
+  // Constructs a DataReceiver to receive data from |source|, using a data
+  // pipe with a buffer size of |buffer_size|, with connection errors reported
+  // as |fatal_error_value|.
+  DataReceiver(mojo::InterfacePtr<serial::DataSource> source,
+               uint32_t buffer_size,
+               int32_t fatal_error_value);
+
+  // Begins a receive operation. If this returns true, exactly one of |callback|
+  // and |error_callback| will eventually be called. If there is already a
+  // receive in progress, |callback| or |error_callback| is invalid or there has
+  // been a connection error, this will have no effect and return false.
+  bool Receive(const ReceiveDataCallback& callback,
+               const ReceiveErrorCallback& error_callback);
+
+ private:
+  class PendingReceive;
+  struct PendingError;
+  friend class base::RefCounted<DataReceiver>;
+
+  virtual ~DataReceiver();
+
+  // serial::DataSourceClient override.
+  virtual void OnError(uint32_t bytes_since_last_error, int32_t error) OVERRIDE;
+
+  // mojo::ErrorHandler override.
+  virtual void OnConnectionError() OVERRIDE;
+
+  void Done(uint32_t bytes_consumed);

[raymes, 2014/08/06 05:46:43]

Please add comments for each of these methods and the member variables below.

[Sam McNally, 2014/08/06 08:28:14]

Done.

+  void OnDoneWaiting(MojoResult result);
+
+  void ReceiveInternal();
+
+  bool CheckBytesReceived(uint32_t num_bytes);
+
+  void ShutDown();
+
+  mojo::InterfacePtr<serial::DataSource> source_;
+  const int32_t fatal_error_value_;
+  mojo::ScopedDataPipeConsumerHandle handle_;
+  uint32_t bytes_received_;
+  bool shut_down_;
+  scoped_ptr<AsyncWaiter> waiter_;
+  scoped_ptr<PendingReceive> receive_;
+  scoped_ptr<PendingError> error_;
+  base::WeakPtrFactory<DataReceiver> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(DataReceiver);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_SERIAL_DATA_RECEIVER_H_