Use the user's preferred downloads directory for creating the initial download file.

content/browser/download/download_file_impl.cc

Index: content/browser/download/download_file_impl.cc
diff --git a/content/browser/download/download_file_impl.cc b/content/browser/download/download_file_impl.cc
index a1ab62a1a8908cb5b000f2c478d68da81bcc5464..d9cb094bb2f291ba13078b63a90b4a1ee631cef1 100644
--- a/content/browser/download/download_file_impl.cc
+++ b/content/browser/download/download_file_impl.cc
@@ -35,7 +35,8 @@ DownloadFileImpl::DownloadFileImpl(
     bool calculate_hash,
     scoped_ptr<content::PowerSaveBlocker> power_save_blocker,
     const net::BoundNetLog& bound_net_log)
-        : file_(info->save_info.file_path,
+        : file_(info->default_download_directory,
+                info->save_info.file_path,
                 info->url(),
                 info->referrer_url,
                 info->received_bytes,