int render_process_id,
int render_frame_id,
const content::URLDataSource::GotDataCallback& callback) {
+ if (!profile_->GetTopSites()) {
+ callback.Run(NULL);
+ return;
+ }
+
profile_->GetTopSites()->GetMostVisitedURLs(
base::Bind(&ThumbnailListSource::OnMostVisitedURLsAvailable,
weak_ptr_factory_.GetWeakPtr(),