Mojo: Implement plumbing to support passing handles over MessagePipes.

mojo/system/message_pipe_dispatcher.h

Index: mojo/system/message_pipe_dispatcher.h
diff --git a/mojo/system/message_pipe_dispatcher.h b/mojo/system/message_pipe_dispatcher.h
index a0e2f09130b46f8a3bf0bec96c4e77080ebd0e8d..8fda16ab837c772200814874c12622b941406460 100644
--- a/mojo/system/message_pipe_dispatcher.h
+++ b/mojo/system/message_pipe_dispatcher.h
@@ -33,16 +33,13 @@ class MOJO_SYSTEM_EXPORT MessagePipeDispatcher : public Dispatcher {
   virtual void CancelAllWaitersNoLock() OVERRIDE;
   virtual MojoResult CloseImplNoLock() OVERRIDE;
   virtual MojoResult WriteMessageImplNoLock(
-      const void* bytes,
-      uint32_t num_bytes,
-      const MojoHandle* handles,
-      uint32_t num_handles,
+      const void* bytes, uint32_t num_bytes,
+      const std::vector<Dispatcher*>* dispatchers,
       MojoWriteMessageFlags flags) OVERRIDE;
   virtual MojoResult ReadMessageImplNoLock(
-      void* bytes,
-      uint32_t* num_bytes,
-      MojoHandle* handles,
-      uint32_t* num_handles,
+      void* bytes, uint32_t* num_bytes,
+      uint32_t max_num_dispatchers,
+      std::vector<scoped_refptr<Dispatcher> >* dispatchers,
       MojoReadMessageFlags flags) OVERRIDE;
   virtual MojoResult AddWaiterImplNoLock(Waiter* waiter,
                                          MojoWaitFlags flags,