FYI: Control Data + Per-Device Metadata

sync/internal_api/public/base/model_type.h

Index: sync/internal_api/public/base/model_type.h
diff --git a/sync/internal_api/public/base/model_type.h b/sync/internal_api/public/base/model_type.h
index 20c8ffa19d0a37d860e9170c706d7e58dca0bcba..5e3c71eb8fa2f352c0d760182f3ed5cc62399315 100644
--- a/sync/internal_api/public/base/model_type.h
+++ b/sync/internal_api/public/base/model_type.h
@@ -124,6 +124,12 @@ SYNC_EXPORT ModelType GetModelTypeFromSpecifics(
 // value (sibling ordering) for this item.
 bool ShouldMaintainPosition(ModelType model_type);
 
+// If this returns true, this type belongs in GROUP_CONTROL.  The syncer has
+// special code to deal with its encryption, update application and conflict
+// resolution, so it should not receive any 'generic' processing for those
+// purposes.
+bool IsControlType(ModelType model_type);
+
 // Determine a model type from the field number of its associated
 // EntitySpecifics field.
 ModelType GetModelTypeFromSpecificsFieldNumber(int field_number);