Enable Null Syncable ID which is different than Root ID.

sync/internal_api/sync_manager_impl_unittest.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.
 
 // Unit tests for the SyncApi. Note that a lot of the underlying
 // functionality is provided by the Syncable layer, which has its own
 // unit tests. We'll test SyncApi specific things in this harness.
 
 #include <cstddef>
 #include <map>
@@ skipping 137 matching lines @@
       FROM_HERE, syncable::UNITTEST, share->directory.get());
   // Attempt to lookup by nigori tag.
   std::string type_tag = ModelTypeToRootTag(model_type);
   syncable::Id node_id = syncable::Id::CreateFromServerId(type_tag);
   syncable::MutableEntry entry(&trans, syncable::CREATE_NEW_UPDATE_ITEM,
                                node_id);
   EXPECT_TRUE(entry.good());
   entry.PutBaseVersion(1);
   entry.PutServerVersion(1);
   entry.PutIsUnappliedUpdate(false);
-  entry.PutServerParentId(syncable::GetNullId());
+  // TODO(stanisc): setting parent ID might be unnecessary once
+  // empty parent ID is supported.
+  entry.PutParentId(syncable::Id::GetRoot());
+  entry.PutServerParentId(syncable::Id::GetRoot());
   entry.PutServerIsDir(true);
   entry.PutIsDir(true);
   entry.PutServerSpecifics(specifics);
   entry.PutUniqueServerTag(type_tag);
   entry.PutNonUniqueName(type_tag);
   entry.PutIsDel(false);
   entry.PutSpecifics(specifics);
   return entry.GetMetahandle();
 }
 
@@ skipping 3005 matching lines @@
 // SyncManagerInitInvalidStorageTest::GetFactory will return
 // DirectoryBackingStore that ensures that SyncManagerImpl::OpenDirectory fails.
 // SyncManagerImpl initialization is done in SyncManagerTest::SetUp. This test's
 // task is to ensure that SyncManagerImpl reported initialization failure in
 // OnInitializationComplete callback.
 TEST_F(SyncManagerInitInvalidStorageTest, FailToOpenDatabase) {
   EXPECT_FALSE(initialization_succeeded_);
 }
 
 }  // namespace syncer