No need to pass DownloadItemModel ownership.

chrome/browser/ui/cocoa/download/download_shelf_mac.mm

 // 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/ui/cocoa/download/download_shelf_mac.h"
 
 #include "chrome/browser/download/download_item_model.h"
 #include "chrome/browser/ui/browser.h"
 #import "chrome/browser/ui/cocoa/download/download_shelf_controller.h"
 #include "chrome/browser/ui/cocoa/download/download_item_mac.h"
 
 DownloadShelfMac::DownloadShelfMac(Browser* browser,
                                    DownloadShelfController* controller)
     : browser_(browser),
       shelf_controller_(controller) {
 }
 
-void DownloadShelfMac::DoAddDownload(DownloadItemModel* download_model) {
-  [shelf_controller_ addDownloadItem:download_model];
+void DownloadShelfMac::DoAddDownload(content::DownloadItem* download) {
+  [shelf_controller_ addDownloadItem:download];
 }
 
 bool DownloadShelfMac::IsShowing() const {
   return [shelf_controller_ isVisible] == YES;
 }
 
 bool DownloadShelfMac::IsClosing() const {
   // TODO(estade): This is never called. For now just return false.
   return false;
 }
 
 void DownloadShelfMac::DoShow() {
   [shelf_controller_ show:nil];
   browser_->UpdateDownloadShelfVisibility(true);
 }
 
 void DownloadShelfMac::DoClose() {
   [shelf_controller_ hide:nil];
   browser_->UpdateDownloadShelfVisibility(false);
 }
 
 Browser* DownloadShelfMac::browser() const {
   return browser_;
 }