Decouple Blimp transport output from BlimpConnections using MessagePort.

blimp/net/message_port.h

Index: blimp/net/message_port.h
diff --git a/blimp/net/message_port.h b/blimp/net/message_port.h
new file mode 100644
index 0000000000000000000000000000000000000000..42d2603348a2e510a227f3c6ad405862540e1372
--- /dev/null
+++ b/blimp/net/message_port.h
@@ -0,0 +1,38 @@
+// 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.
+
+#ifndef BLIMP_NET_MESSAGE_PORT_H_
+#define BLIMP_NET_MESSAGE_PORT_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/supports_user_data.h"
+#include "blimp/net/blimp_net_export.h"
+
+namespace blimp {
+
+class PacketReader;
+class PacketWriter;
+
+// A duplexed pair of a framed reader and writer.
+class BLIMP_NET_EXPORT MessagePort : public base::SupportsUserData {
+ public:
+  MessagePort(std::unique_ptr<PacketReader> reader,
+              std::unique_ptr<PacketWriter> writer);
+  ~MessagePort() override;
+
+  PacketReader* reader() const { return reader_.get(); }
+  PacketWriter* writer() const { return writer_.get(); }
+
+ private:
+  std::unique_ptr<PacketReader> reader_;
+  std::unique_ptr<PacketWriter> writer_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessagePort);
+};
+
+}  // namespace blimp
+
+#endif  // BLIMP_NET_MESSAGE_PORT_H_