[Chromoting] Remove DataChannelManagerCallbacks constructor parameter of ClientSession

remoting/host/client_session.h

Index: remoting/host/client_session.h
diff --git a/remoting/host/client_session.h b/remoting/host/client_session.h
index d0c830bc1c50308b1af2b51e8fa154a747bb55cc..c439355b61f7c51c33d7a45a014c379099bfe876 100644
--- a/remoting/host/client_session.h
+++ b/remoting/host/client_session.h
@@ -97,9 +97,7 @@ class ClientSession : public protocol::HostStub,
       const DesktopEnvironmentOptions& desktop_environment_options,
       const base::TimeDelta& max_duration,
       scoped_refptr<protocol::PairingRegistry> pairing_registry,
-      const std::vector<HostExtension*>& extensions,
-      const std::vector<protocol::DataChannelManager::NameCallbackPair>&
-          data_channel_callbacks);
+      const std::vector<HostExtension*>& extensions);
   ~ClientSession() override;
 
   // Returns the set of capabilities negotiated between client and host.
@@ -145,6 +143,11 @@ class ClientSession : public protocol::HostStub,
     return client_capabilities_.get();
   }
 
+  // Registers a DataChannelManager callback for testing.
+  void RegisterCreateHandlerCallbackForTesting(
+      const std::string& prefix,
+      protocol::DataChannelManager::CreateHandlerCallback constructor);
+
   void SetEventTimestampsSourceForTests(
       scoped_refptr<protocol::InputEventTimestampsSource>
           event_timestamp_source);