[Chromoting] Remove DataChannelManagerCallbacks constructor parameter of ClientSession

remoting/protocol/data_channel_manager.h

 // 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)>;
 
-  using NameCallbackPair = std::pair<std::string, CreateHandlerCallback>;
-
   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<NameCallbackPair> constructors_;
+  std::vector<std::pair<std::string, CreateHandlerCallback>> constructors_;
 };
 
 }  // namespace protocol
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_DATA_CHANNEL_MANAGER_H_