Fixed inconsistent type for RegisterCallbacks

Change-Id: Id3193430b61f5d0005370d7dd5f298d5f25a7dfa
Reviewed-on: https://weave-review.googlesource.com/1293
Reviewed-by: Vitaly Buka <vitalybuka@google.com>

libweave/src/device_registration_info.h

diff --git a/libweave/src/device_registration_info.h b/libweave/src/device_registration_info.h
index fdc4dcd..8d230a9 100644
--- a/libweave/src/device_registration_info.h
+++ b/libweave/src/device_registration_info.h
@@ -275,7 +275,7 @@
   // Wipes out the device registration information and stops server connections.
   void MarkDeviceUnregistered();
 
-  class RegisterCallbacks;
+  struct RegisterCallbacks;
   void RegisterDeviceError(const std::shared_ptr<RegisterCallbacks>& callbacks,
                            const Error* error);
   void RegisterDeviceOnTicketSent(