sync: Process 'control' data separately

sync/engine/apply_updates_command.cc

Index: sync/engine/apply_updates_command.cc
diff --git a/sync/engine/apply_updates_command.cc b/sync/engine/apply_updates_command.cc
index fd18ff225161d4109bb81ba94a3d3e815ebae364..b8072671cb4f0524596fda892084ea8ff1e1503a 100644
--- a/sync/engine/apply_updates_command.cc
+++ b/sync/engine/apply_updates_command.cc
@@ -32,10 +32,15 @@ std::set<ModelSafeGroup> ApplyUpdatesCommand::GetGroupsToChange(
 
   for (syncable::FullModelTypeSet::Iterator it =
            server_types_with_unapplied_updates.First(); it.Good(); it.Inc()) {
+    VLOG(2) << "TYPES: " << ModelTypeToString(it.Get());
     groups_with_unapplied_updates.insert(
         GetGroupForModelType(it.Get(), session.routing_info()));
   }
 
+  // The INTERNAL types are special.  They have their own update routines,
+  // ApplyUpdatesCommand should not process them.
+  groups_with_unapplied_updates.erase(GROUP_CONTROL);
+
   return groups_with_unapplied_updates;
 }