Separate invalidator and sync client ID (part 1/2)

sync/internal_api/public/engine/sync_status.h

Index: sync/internal_api/public/engine/sync_status.h
diff --git a/sync/internal_api/public/engine/sync_status.h b/sync/internal_api/public/engine/sync_status.h
index b8d49bf7c4e49acb27e3a21ca7d2970527b797e5..b28d3613989a54ddfc9d071ab4d08ea7f89d54e9 100644
--- a/sync/internal_api/public/engine/sync_status.h
+++ b/sync/internal_api/public/engine/sync_status.h
@@ -93,8 +93,11 @@ struct SYNC_EXPORT SyncStatus {
   // Per-datatype throttled status.
   ModelTypeSet throttled_types;
 
-  // The unique identifer for this client.
-  std::string unique_id;
+  // The unique identifer for the sync store.
+  std::string sync_id;
+
+  // The unique identifier for the invalidation client.
+  std::string invalidator_client_id;
 
   // Counters grouped by model type
   std::vector<int> num_entries_by_type;