[Sync] Make GetFirstChildId return a flag indicating success

chrome/browser/sync/engine/apply_updates_command_unittest.cc

 // Copyright (c) 2011 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 <string>
 
 #include "base/format_macros.h"
 #include "base/location.h"
 #include "base/stringprintf.h"
 #include "chrome/browser/sync/engine/apply_updates_command.h"
@@ skipping 95 matching lines @@
   // Returns the methandle of the created item in |metahandle_out| if not NULL.
   void CreateUnsyncedItem(const Id& item_id,
                           const Id& parent_id,
                           const string& name,
                           bool is_folder,
                           syncable::ModelType model_type,
                           int64* metahandle_out) {
     ScopedDirLookup dir(syncdb()->manager(), syncdb()->name());
     ASSERT_TRUE(dir.good());
     WriteTransaction trans(FROM_HERE, UNITTEST, dir);
-    Id predecessor_id = dir->GetLastChildId(&trans, parent_id);
+    Id predecessor_id;
+    ASSERT_TRUE(
+        dir->GetLastChildIdForTest(&trans, parent_id, &predecessor_id));
     MutableEntry entry(&trans, syncable::CREATE, parent_id, name);
     ASSERT_TRUE(entry.good());
     entry.Put(syncable::ID, item_id);
     entry.Put(syncable::BASE_VERSION,
         item_id.ServerKnows() ? next_revision_++ : 0);
     entry.Put(syncable::IS_UNSYNCED, true);
     entry.Put(syncable::IS_DIR, is_folder);
     entry.Put(syncable::IS_DEL, false);
     entry.Put(syncable::PARENT_ID, parent_id);
     CHECK(entry.PutPredecessor(predecessor_id));
@@ skipping 549 matching lines @@
     encrypted_types.insert(syncable::BOOKMARKS);
     EXPECT_EQ(GetAllRealModelTypes(), cryptographer->GetEncryptedTypes());
 
     Syncer::UnsyncedMetaHandles handles;
     SyncerUtil::GetUnsyncedEntries(&trans, &handles);
     EXPECT_EQ(2*batch_s+1, handles.size());
   }
 }
 
 }  // namespace browser_sync