Update GnubbyAuthHandler to use the current session ID

remoting/host/host_extension_session.h

 // Copyright 2014 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_HOST_HOST_EXTENSION_SESSION_H_
 #define REMOTING_HOST_HOST_EXTENSION_SESSION_H_
 
-namespace webrtc {
-class DesktopCapturer;
-}
-
 namespace remoting {
 
 class ClientSessionDetails;
-class VideoEncoder;
 
 namespace protocol {
 class ExtensionMessage;
 class ClientStub;
 }  // namespace protocol
 
 // Created by an |HostExtension| to store |ClientSession| specific state, and to
 // handle extension messages.
 class HostExtensionSession {
  public:
   virtual ~HostExtensionSession() {}
 
   // Called when the host receives an |ExtensionMessage| for the |ClientSession|
   // associated with this |HostExtensionSession|.
   // It returns |true| if the message was handled, and |false| otherwise.
   virtual bool OnExtensionMessage(
       ClientSessionDetails* client_session_details,
       protocol::ClientStub* client_stub,
       const protocol::ExtensionMessage& message) = 0;
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_HOST_EXTENSION_SESSION_H_