EDK: Convert remaining scoped_ptr -> std::unique_ptr in //mojo/edk/system.

mojo/edk/system/incoming_endpoint.cc

Index: mojo/edk/system/incoming_endpoint.cc
diff --git a/mojo/edk/system/incoming_endpoint.cc b/mojo/edk/system/incoming_endpoint.cc
index eaa1825a9f4fac9890c632f23b7f0036ae161ae0..d92cf49992085fe8b6c5ba3b34a2564afaee58cb 100644
--- a/mojo/edk/system/incoming_endpoint.cc
+++ b/mojo/edk/system/incoming_endpoint.cc
@@ -67,7 +67,7 @@ bool IncomingEndpoint::OnReadMessage(unsigned /*port*/,
   if (!endpoint_)
     return false;
 
-  message_queue_.AddMessage(make_scoped_ptr(message));
+  message_queue_.AddMessage(std::unique_ptr<MessageInTransit>(message));
   return true;
 }