sync: Process 'control' data separately

sync/internal_api/public/engine/model_safe_worker.h

Index: sync/internal_api/public/engine/model_safe_worker.h
diff --git a/sync/internal_api/public/engine/model_safe_worker.h b/sync/internal_api/public/engine/model_safe_worker.h
index 1a6c371fd0ff5cc5dc1afa1293e9f69657d7ea4e..3a6cf66c45c241b65ca5ccc4cc6cd84ecc76f47c 100644
--- a/sync/internal_api/public/engine/model_safe_worker.h
+++ b/sync/internal_api/public/engine/model_safe_worker.h
@@ -35,6 +35,8 @@ enum ModelSafeGroup {
   GROUP_PASSWORD,      // Models that live on the password thread and are
                        // being synced.  On windows and linux, this runs on the
                        // DB thread.
+  GROUP_INTERNAL,      // Models that require special handling on the sync

[Nicolas Zea, 2012/06/21 02:58:36]

It's not clear to me why this is different (or needs a separate model worker)
than GROUP_PASSIVE? The whole point of passive is for those types that are
handled on the sync thread and don't have an associated native model.

Could we just get away with having the logic conditional on GROUP_INTERNAL be
conditional on GROUP_PASSIVE instead?

[rlarocque, 2012/06/21 18:23:27]

I added this so I could exclude these types from regular processing in some
ModelChangingSyncerCommands.  I couldn't use GROUP_PASSIVE, since that is also
used for initializing other data types that eventually reside on other threads. 


Now that I see the effect this is having on tests, I'm not so sure it is the
right approach.

+                       // thread.  These types have no associated model.
   MODEL_SAFE_GROUP_COUNT,
 };