Introduce a fake HostStub since there's no need to handle it now

remoting/host/chromoting_host.h

Index: remoting/host/chromoting_host.h
diff --git a/remoting/host/chromoting_host.h b/remoting/host/chromoting_host.h
index ab285ab6c59b32caa61295c08b67adea2596da1c..f3b908f8d63712f96ce96a48d3077d58a3b64f57 100644
--- a/remoting/host/chromoting_host.h
+++ b/remoting/host/chromoting_host.h
@@ -14,7 +14,6 @@
 #include "remoting/host/heartbeat_sender.h"
 #include "remoting/jingle_glue/jingle_client.h"
 #include "remoting/jingle_glue/jingle_thread.h"
-#include "remoting/protocol/input_stub.h"
 #include "remoting/protocol/session_manager.h"
 #include "remoting/protocol/connection_to_client.h"
 
@@ -24,6 +23,8 @@ namespace remoting {
 
 namespace protocol {
 class ConnectionToClient;
+class HostStub;
+class InputStub;
 class SessionConfig;
 }  // namespace protocol
 
@@ -133,6 +134,9 @@ class ChromotingHost : public base::RefCountedThreadSafe<ChromotingHost>,
   // InputStub in the host executes input events received from the client.
   scoped_ptr<protocol::InputStub> input_stub_;
 
+  // HostStub in the host executes control events received from the client.
+  scoped_ptr<protocol::HostStub> host_stub_;
+
   // The libjingle client. This is used to connect to the talk network to
   // receive connection requests from chromoting client.
   scoped_refptr<JingleClient> jingle_client_;