Make client tag IDs consistent in sync fake server

sync/test/fake_server/fake_server.cc

Index: sync/test/fake_server/fake_server.cc
diff --git a/sync/test/fake_server/fake_server.cc b/sync/test/fake_server/fake_server.cc
index b73ef1ae7030c151dcb89a424a2a72d9f12e1a26..854eabec6c5b8207afac3d95b00df2c23af78219 100644
--- a/sync/test/fake_server/fake_server.cc
+++ b/sync/test/fake_server/fake_server.cc
@@ -336,13 +336,7 @@ string FakeServer::CommitEntity(
         client_entity,
         entities_[client_entity.id_string()]);
   } else if (client_entity.has_client_defined_unique_tag()) {
-    if (entities_.find(client_entity.id_string()) != entities_.end()) {
-      entity = UniqueClientEntity::CreateUpdatedVersion(
-          client_entity,
-          entities_[client_entity.id_string()]);
-    } else {
-      entity = UniqueClientEntity::CreateNew(client_entity);
-    }
+    entity = UniqueClientEntity::Create(client_entity);
   } else {
     // TODO(pvalenzuela): Validate entity's parent ID.
     if (entities_.find(client_entity.id_string()) != entities_.end()) {