Add TransportSession interface to prepare for WebRTC-based transport.

remoting/protocol/session.h

Index: remoting/protocol/session.h
diff --git a/remoting/protocol/session.h b/remoting/protocol/session.h
index 6fcd2c61993cb3efdb591b71e4880993f531ed49..4f068f83f0ddc9d7b1118dfcd48d98382fb916c8 100644
--- a/remoting/protocol/session.h
+++ b/remoting/protocol/session.h
@@ -10,14 +10,11 @@
 #include "remoting/protocol/errors.h"
 #include "remoting/protocol/session_config.h"
 
-namespace net {
-class IPEndPoint;
-}  // namespace net
-
 namespace remoting {
 namespace protocol {
 
 class StreamChannelFactory;
+class TransportSession;
 struct TransportRoute;
 
 // Generic interface for Chromotocol connection used by both client and host.
@@ -85,11 +82,11 @@ class Session {
   // Returned pointer is valid until connection is closed.
   virtual const SessionConfig& config() = 0;
 
-  // GetTransportChannelFactory() returns a factory that creates a new transport
-  // channel for each logical channel. GetMultiplexedChannelFactory() channels
-  // share a single underlying transport channel
-  virtual StreamChannelFactory* GetTransportChannelFactory() = 0;
-  virtual StreamChannelFactory* GetMultiplexedChannelFactory() = 0;
+  // Returns TransportSession that can be used to create transport channels.
+  virtual TransportSession* GetTransportSession() = 0;
+
+  // Channel factory for QUIC-based channels. Returns nullptr when QUIC is
+  // disabled for the session.
   virtual StreamChannelFactory* GetQuicChannelFactory() = 0;
 
   // Closes connection. Callbacks are guaranteed not to be called