[Sync] Add HasChildren() function and use it instead of GetFirstChildId()

chrome/browser/sync/glue/theme_model_associator.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 "chrome/browser/sync/glue/theme_model_associator.h"
 
 #include "base/basictypes.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/utf_string_conversions.h"
@@ skipping 78 matching lines @@
   DCHECK(has_nodes);
   *has_nodes = false;
   sync_api::ReadTransaction trans(FROM_HERE, sync_service_->GetUserShare());
   sync_api::ReadNode root(&trans);
   if (!root.InitByTagLookup(kThemesTag)) {
     LOG(ERROR) << kNoThemesFolderError;
     return false;
   }
   // The sync model has user created nodes iff the themes folder has
   // any children.
-  *has_nodes = root.GetFirstChildId() != sync_api::kInvalidId;
+  *has_nodes = root.HasChildren();
   return true;
 }
 
 bool ThemeModelAssociator::CryptoReadyIfNecessary() {
   // We only access the cryptographer while holding a transaction.
   sync_api::ReadTransaction trans(FROM_HERE, sync_service_->GetUserShare());
   syncable::ModelTypeSet encrypted_types;
   encrypted_types = sync_api::GetEncryptedTypes(&trans);
   return encrypted_types.count(syncable::THEMES) == 0 ||
          sync_service_->IsCryptographerReady(&trans);
 }
 
 }  // namespace browser_sync