Decouple Blimp transport output from BlimpConnections using MessagePort.

blimp/net/message_port_util.cc

Index: blimp/net/message_port_util.cc
diff --git a/blimp/net/message_port_util.cc b/blimp/net/message_port_util.cc
new file mode 100644
index 0000000000000000000000000000000000000000..45cfcc37ac95bf520f17a727d871c187f447b9c6
--- /dev/null
+++ b/blimp/net/message_port_util.cc
@@ -0,0 +1,53 @@
+// 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_util.h"
+
+#include <utility>
+
+#include "base/memory/ptr_util.h"
+#include "blimp/net/compressed_packet_reader.h"
+#include "blimp/net/compressed_packet_writer.h"
+#include "blimp/net/message_port.h"
+#include "blimp/net/stream_packet_reader.h"
+#include "blimp/net/stream_packet_writer.h"
+#include "net/socket/stream_socket.h"
+
+namespace blimp {
+namespace {
+
+const char kMessagePortUtilAttachment[] = "message_port_util_attachment";
+
+// Used to bind a Socket lifetime to an object which extends
+// base::SupportsUserData.
+class StreamSocketUserData : public base::SupportsUserData::Data {
+ public:
+  explicit StreamSocketUserData(std::unique_ptr<net::StreamSocket> socket)
+      : socket_(std::move(socket)) {}
+  ~StreamSocketUserData() override = default;
+
+ private:
+  std::unique_ptr<net::StreamSocket> socket_;
+  DISALLOW_COPY_AND_ASSIGN(StreamSocketUserData);
+};
+
+}  // namespace
+
+std::unique_ptr<MessagePort> CreateMessagePortForStreamSocket(
+    std::unique_ptr<net::StreamSocket> socket) {
+  // Use compressed packet readers and writers.
+  std::unique_ptr<MessagePort> output(
+      new MessagePort(base::MakeUnique<CompressedPacketReader>(
+                          base::MakeUnique<StreamPacketReader>(socket.get())),
+                      base::MakeUnique<CompressedPacketWriter>(
+                          base::MakeUnique<StreamPacketWriter>(socket.get()))));
+
+  // Bind |socket|'s lifetime to the MessagePort, so that ownership doesn't need
+  // to be coordinated with the reader or the writer objects.
+  output->SetUserData(kMessagePortUtilAttachment,
+                      new StreamSocketUserData(std::move(socket)));
+  return output;
+}
+
+}  // namespace blimp