[Chromoting] Add DataChannelManager to manage optional incoming data channels

remoting/protocol/data_channel_manager.h

Index: remoting/protocol/data_channel_manager.h
diff --git a/remoting/protocol/data_channel_manager.h b/remoting/protocol/data_channel_manager.h
new file mode 100644
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+++ b/remoting/protocol/data_channel_manager.h
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+// Copyright 2017 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 REMOTING_PROTOCOL_DATA_CHANNEL_MANAGER_H_
+#define REMOTING_PROTOCOL_DATA_CHANNEL_MANAGER_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+
+namespace remoting {
+namespace protocol {
+
+class MessagePipe;
+
+// DataChannelManager helps to manage optional data channels. Consumers can
+// register a function to handle data from a named data channel.
+class DataChannelManager final {
+ public:
+  using CreateHandlerCallback = base::Callback<void(
+      const std::string& name,
+      std::unique_ptr<MessagePipe> pipe)>;
+
+  DataChannelManager();
+  ~DataChannelManager();
+
+  // Registers a factory function to handle a new incoming data channel with a
+  // name matching |prefix|. Both |constructor| and |prefix| cannot be empty.
+  void RegisterCreateHandlerCallback(const std::string& prefix,
+                                     CreateHandlerCallback constructor);
+
+  // Executes the registered callback to handle the new incoming data channel.
+  // Returns true if a handler of the new data channel has been executed.
+  bool OnIncomingDataChannel(const std::string& name,
+                             std::unique_ptr<MessagePipe> pipe);
+
+ private:
+  std::vector<std::pair<std::string, CreateHandlerCallback>> constructors_;
+};
+
+}  // namespace protocol
+}  // namespace remoting
+
+#endif  // REMOTING_PROTOCOL_DATA_CHANNEL_MANAGER_H_