sync: Specialize functions that fetch type root

sync/syncable/directory.cc

Index: sync/syncable/directory.cc
diff --git a/sync/syncable/directory.cc b/sync/syncable/directory.cc
index 39233fee410acda35fcbb382f9473725a0ad6bdd..ad107b1c28ca4d9e4b2f342398ad27ec8e6204fa 100644
--- a/sync/syncable/directory.cc
+++ b/sync/syncable/directory.cc
@@ -952,9 +952,7 @@ bool Directory::InitialSyncEndedForType(ModelType type) {
 bool Directory::InitialSyncEndedForType(
     BaseTransaction* trans, ModelType type) {
   // True iff the type's root node has been received and applied.
-  syncable::Entry entry(trans,
-                        syncable::GET_BY_SERVER_TAG,
-                        ModelTypeToRootTag(type));
+  syncable::Entry entry(trans, syncable::GET_TYPE_ROOT, type);
   return entry.good() && entry.GetBaseVersion() != CHANGES_VERSION;
 }