Add the plumbing that will carry a clipboard item from a chromoting client to a host.

remoting/host/event_executor.h

Index: remoting/host/event_executor.h
diff --git a/remoting/host/event_executor.h b/remoting/host/event_executor.h
index 6051b362a3eb7656224330f39b16f80ea0a90524..47398d6e2b52d999a51817a9c6b3c0fa8f382e22 100644
--- a/remoting/host/event_executor.h
+++ b/remoting/host/event_executor.h
@@ -5,6 +5,7 @@
 #ifndef REMOTING_HOST_EVENT_EXECUTOR_H_
 #define REMOTING_HOST_EVENT_EXECUTOR_H_
 
+#include "remoting/protocol/clipboard_stub.h"
 #include "remoting/protocol/input_stub.h"
 
 class MessageLoop;
@@ -13,7 +14,8 @@ namespace remoting {
 
 class Capturer;
 
-class EventExecutor : public protocol::InputStub {
+class EventExecutor : public protocol::ClipboardStub,
+                      public protocol::InputStub {
  public:
   // Creates default event executor for the current platform.
   // Does not take ownership of |message_loop| or |capturer|.