No need to pass DownloadItemModel ownership.

chrome/browser/ui/gtk/download/download_shelf_context_menu_gtk.cc

Index: chrome/browser/ui/gtk/download/download_shelf_context_menu_gtk.cc
diff --git a/chrome/browser/ui/gtk/download/download_shelf_context_menu_gtk.cc b/chrome/browser/ui/gtk/download/download_shelf_context_menu_gtk.cc
index 1441a937ab800973c24df34dfcff4c22888ee490..43b45efc0b46738dda2c895f4a95d70f5abc982e 100644
--- a/chrome/browser/ui/gtk/download/download_shelf_context_menu_gtk.cc
+++ b/chrome/browser/ui/gtk/download/download_shelf_context_menu_gtk.cc
@@ -11,10 +11,9 @@
 #include "ui/gfx/point.h"
 
 DownloadShelfContextMenuGtk::DownloadShelfContextMenuGtk(
-    DownloadItemModel* model,
     DownloadItemGtk* download_item,
     content::PageNavigator* navigator)
-    : DownloadShelfContextMenu(model, navigator),
+    : DownloadShelfContextMenu(download_item->download(), navigator),
       download_item_gtk_(download_item) {
 }
 
@@ -22,7 +21,13 @@ DownloadShelfContextMenuGtk::~DownloadShelfContextMenuGtk() {}
 
 void DownloadShelfContextMenuGtk::Popup(GtkWidget* widget,
                                         GdkEventButton* event) {
-  menu_.reset(new MenuGtk(this, GetMenuModel()));
+  ui::SimpleMenuModel* menu_model = GetMenuModel();
+  if (!menu_model) {
+    StoppedShowing();
+    return;
+  }
+
+  menu_.reset(new MenuGtk(this, menu_model));
 
   if (widget)
     menu_->PopupForWidget(widget, event->button, event->time);