No need to pass DownloadItemModel ownership.

chrome/browser/download/download_shelf.cc

 // Copyright (c) 2012 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/download/download_shelf.h"
 
 DownloadShelf::DownloadShelf()
     : should_show_on_unhide_(false),
       is_hidden_(false) {}
 
-void DownloadShelf::AddDownload(DownloadItemModel* download_model) {
+void DownloadShelf::AddDownload(content::DownloadItem* download) {
   if (is_hidden_)
     Unhide();
   Show();
-  DoAddDownload(download_model);
+  DoAddDownload(download);
 }
 
 void DownloadShelf::Show() {
   if (is_hidden_) {
     should_show_on_unhide_ = true;
     return;
   }
   DoShow();
 }
 
@@ skipping 17 matching lines @@
 
 void DownloadShelf::Unhide() {
   if (!is_hidden_)
     return;
   is_hidden_ = false;
   if (should_show_on_unhide_) {
     should_show_on_unhide_ = false;
     DoShow();
   }
 }