sync: Introduce control data types

sync/engine/apply_updates_command.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sync/engine/apply_updates_command.h"
 
 #include "base/location.h"
 #include "sync/engine/update_applicator.h"
 #include "sync/sessions/sync_session.h"
 #include "sync/syncable/directory.h"
@@ skipping 18 matching lines @@
     server_types_with_unapplied_updates =
         dir->GetServerTypesWithUnappliedUpdates(&trans);
   }
 
   for (FullModelTypeSet::Iterator it =
            server_types_with_unapplied_updates.First(); it.Good(); it.Inc()) {
     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;
 }
 
 SyncerError ApplyUpdatesCommand::ModelChangingExecuteImpl(
     SyncSession* session) {
   syncable::Directory* dir = session->context()->directory();
   syncable::WriteTransaction trans(FROM_HERE, syncable::SYNCER, dir);
 
   // Compute server types with unapplied updates that fall under our
   // group restriction.
@@ skipping 30 matching lines @@
              status.updates_request_types().First(); it.Good(); it.Inc()) {
       // This gets persisted to the directory's backing store.
       dir->set_initial_sync_ended_for_type(it.Get(), true);
     }
   }
 
   return SYNCER_OK;
 }
 
 }  // namespace syncer