EDK: Plumb Handle/HandleVector yet one more layer down: MessageInTransit.

mojo/edk/system/transport_data.h

Index: mojo/edk/system/transport_data.h
diff --git a/mojo/edk/system/transport_data.h b/mojo/edk/system/transport_data.h
index 771e071cd34ae6bce5a851a5b1e0650e3e9929f2..8698a6d388fe79eff65626062c32dcddba9c3a34 100644
--- a/mojo/edk/system/transport_data.h
+++ b/mojo/edk/system/transport_data.h
@@ -86,6 +86,8 @@ class TransportData {
   // The maximum total number of platform handles that may be attached.
   static size_t GetMaxPlatformHandles();
 
+  TransportData(std::unique_ptr<HandleVector> handles, Channel* channel);
+  // TODO(vtl): Remove this, once |TransportData| really supports handles.
   TransportData(std::unique_ptr<DispatcherVector> dispatchers,
                 Channel* channel);