Initial download shelf on OS X....

chrome/browser/download/download_manager.cc

Index: chrome/browser/download/download_manager.cc
===================================================================
--- chrome/browser/download/download_manager.cc	(revision 18653)
+++ chrome/browser/download/download_manager.cc	(working copy)
@@ -636,6 +636,7 @@
   DCHECK(info);
 
   if (info->save_as) {
+#if defined(OS_WIN) || defined(OS_LINUX)
     // We must ask the user for the place to put the download.
     if (!select_file_dialog_.get())
       select_file_dialog_ = SelectFileDialog::Create(this);
@@ -655,6 +656,10 @@
                                     info->suggested_path,
                                     &file_type_info, 0, FILE_PATH_LITERAL(""),
                                     owning_window, info);
+#elif defined(OS_MACOSX)
+    // TODO(port): port this file -- need dialogs.
+    NOTIMPLEMENTED();
+#endif
   } else {
     // No prompting for download, just continue with the suggested name.
     ContinueStartDownload(info, info->suggested_path);