Enable Null Syncable ID which is different than Root ID.

sync/internal_api/test/test_entry_factory.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sync/internal_api/public/test/test_entry_factory.h"
 
 #include "sync/syncable/directory.h"
 #include "sync/syncable/entry.h"
 #include "sync/syncable/mutable_entry.h"
 #include "sync/syncable/syncable_id.h"
@@ skipping 58 matching lines @@
     const string& item_id,
     const sync_pb::EntitySpecifics& specifics,
     bool is_unique) {
   WriteTransaction trans(FROM_HERE, UNITTEST, directory_);
   MutableEntry entry(&trans, syncable::CREATE_NEW_UPDATE_ITEM,
       Id::CreateFromServerId(item_id));
   DCHECK(entry.good());
   entry.PutServerVersion(GetNextRevision());
   entry.PutIsUnappliedUpdate(true);
   entry.PutServerNonUniqueName(item_id);
-  entry.PutServerParentId(syncable::GetNullId());
+  entry.PutServerParentId(syncable::Id::GetRoot());
   entry.PutServerIsDir(is_unique);
   entry.PutServerSpecifics(specifics);
   if (is_unique) { // For top-level nodes.
     entry.PutUniqueServerTag(
               ModelTypeToRootTag(GetModelTypeFromSpecifics(specifics)));
   }
   return entry.GetMetahandle();
 }
 
 void TestEntryFactory::CreateUnsyncedItem(
@@ skipping 210 matching lines @@
     return false;
   }
   return entry.GetIsUnappliedUpdate();
 }
 
 int64 TestEntryFactory::GetNextRevision() {
   return next_revision_++;
 }
 
 }  // namespace syncer