Blimp: create MessageDispatcher class.

blimp/net/blimp_message_dispatcher.h

Index: blimp/net/blimp_message_dispatcher.h
diff --git a/blimp/net/blimp_message_dispatcher.h b/blimp/net/blimp_message_dispatcher.h
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+// Copyright 2015 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_BLIMP_MESSAGE_DISPATCHER_H_
+#define BLIMP_NET_BLIMP_MESSAGE_DISPATCHER_H_
+
+#include <map>
+
+#include "base/containers/small_map.h"
+#include "base/threading/thread_checker.h"
+#include "blimp/common/proto/blimp_message.pb.h"
+#include "blimp/net/blimp_message_receiver.h"
+#include "blimp/net/blimp_net_export.h"
+
+namespace blimp {
+
+// Multiplexing BlimpMessageReceiver which routes BlimpMessages to other
+// receivers based on the messages' feature type.
+class BLIMP_NET_EXPORT BlimpMessageDispatcher : public BlimpMessageReceiver {
+ public:
+  BlimpMessageDispatcher();
+  ~BlimpMessageDispatcher() override;
+
+  // Registers a message receiver which will process all messages
+  // with of the specified |type|.
+  // Only one handler may be added per type.
+  //
+  // |handler| must be valid when OnBlimpMessage() is called.
+  void AddReceiver(BlimpMessage::Type type, BlimpMessageReceiver* handler);
+
+  // BlimpMessageReceiver implementation.
+  net::Error OnBlimpMessage(const BlimpMessage& message) override;
+
+ private:
+  base::SmallMap<std::map<BlimpMessage::Type, BlimpMessageReceiver*>>
+      feature_receiver_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(BlimpMessageDispatcher);
+};
+
+}  // namespace blimp
+
+#endif  // BLIMP_NET_BLIMP_MESSAGE_DISPATCHER_H_