Add MessageChanneFactory interface and use it in ChannelDispatcherBase.

remoting/protocol/message_channel_factory.h

Index: remoting/protocol/message_channel_factory.h
diff --git a/remoting/protocol/message_channel_factory.h b/remoting/protocol/message_channel_factory.h
new file mode 100644
index 0000000000000000000000000000000000000000..430791490c1c64d38d4efaae427a76d6109c48a3
--- /dev/null
+++ b/remoting/protocol/message_channel_factory.h
@@ -0,0 +1,41 @@
+// 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 REMOTING_PROTOCOL_MESSAGE_CHANNEL_FACTORY_H_
+#define REMOTING_PROTOCOL_MESSAGE_CHANNEL_FACTORY_H_
+
+#include <string>
+
+#include "base/callback_forward.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace remoting {
+namespace protocol {
+
+class MessagePipe;
+
+class MessageChannelFactory {
+ public:
+  typedef base::Callback<void(scoped_ptr<MessagePipe>)> ChannelCreatedCallback;
+
+  virtual ~MessageChannelFactory() {}
+
+  // Creates new channels and calls the |callback| when then new channel is
+  // created and connected. Callback may be called synchronously, before the
+  // call returns. If channel creation fails the callback is never called. All
+  // channels must be destroyed, and CancelChannelCreation() called for any
+  // pending channels, before the factory is destroyed.
+  virtual void CreateChannel(const std::string& name,
+                             const ChannelCreatedCallback& callback) = 0;
+
+  // Cancels a pending CreateChannel() operation for the named channel. If the
+  // channel creation already completed then canceling it has no effect. When
+  // shutting down this method must be called for each channel pending creation.
+  virtual void CancelChannelCreation(const std::string& name) = 0;
+};
+
+}  // namespace protocol
+}  // namespace remoting
+
+#endif  // REMOTING_PROTOCOL_MESSAGE_CHANNEL_FACTORY_H_