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) {

[Sergey Ulanov, 2012/03/09 00:23:41]

Would it be better to use control channel for clipboard. It will always be
reliable, while we may change event channel to be unreliable.

[simonmorris, 2012/03/09 00:34:14]

I think it's better to send clipboard events over the same channel as key and
mouse events, if only for consistency.

If the event channel becomes unreliable, presumably the key events (at least)
will move to a reliable channel, so the clipboard events could move at the same
time.

[Wez, 2012/03/09 00:44:07]

We'll have a keyboard-event-specific reliability protocol when we move to an
unreliable channel, so to get reliable clipboard transfer without building a
specialised reliability layer for it, we'll need to put clipboard data on a
separate channel, and used PseudoTcp for that.

+    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_;