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

remoting/protocol/host_event_dispatcher.h

Index: remoting/protocol/host_event_dispatcher.h
diff --git a/remoting/protocol/host_event_dispatcher.h b/remoting/protocol/host_event_dispatcher.h
index 7076af1c6a6845cbc74fdf3fad4af74ec8557197..438d743a504f9d3cecefbfabc67ddd93189b9724 100644
--- a/remoting/protocol/host_event_dispatcher.h
+++ b/remoting/protocol/host_event_dispatcher.h
@@ -11,11 +11,12 @@
 namespace remoting {
 namespace protocol {
 
+class ClipboardStub;
 class EventMessage;
 class InputStub;
 
 // HostEventDispatcher dispatches incoming messages on the event
-// channel to InputStub.
+// channel to InputStub or ClipboardStub.
 class HostEventDispatcher : public ChannelDispatcherBase {
  public:
   typedef base::Callback<void(int64)> SequenceNumberCallback;
@@ -23,6 +24,13 @@ class HostEventDispatcher : public ChannelDispatcherBase {
   HostEventDispatcher();
   virtual ~HostEventDispatcher();
 
+  // Set the ClipboardStub that will be called for each incoming clipboard
+  // message. Doesn't take ownership of |clipboard_stub|. It must outlive
+  // the dispatcher.
+  void set_clipboard_stub(ClipboardStub* clipboard_stub) {
+    clipboard_stub_ = clipboard_stub;
+  }
+
   // Set InputStub that will be called for each incoming input
   // message. Doesn't take ownership of |input_stub|. It must outlive
   // the dispatcher.
@@ -42,6 +50,7 @@ class HostEventDispatcher : public ChannelDispatcherBase {
   void OnMessageReceived(EventMessage* message,
                          const base::Closure& done_task);
 
+  ClipboardStub* clipboard_stub_;
   InputStub* input_stub_;
   SequenceNumberCallback sequence_number_callback_;