Decouple Blimp transport output from BlimpConnections using MessagePort.

blimp/net/message_port.cc

+// Copyright 2016 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.
+
+#include "blimp/net/message_port.h"
+
+#include <utility>
+
+#include "blimp/net/packet_reader.h"
+#include "blimp/net/packet_writer.h"
+
+namespace blimp {
+
+MessagePort::MessagePort(std::unique_ptr<PacketReader> reader,
+                         std::unique_ptr<PacketWriter> writer)
+    : reader_(std::move(reader)), writer_(std::move(writer)) {}
+
+MessagePort::~MessagePort() {}
+
+}  // namespace blimp