No need to pass DownloadItemModel ownership.

chrome/browser/download/download_shelf.h

 // 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.
 
 #ifndef CHROME_BROWSER_DOWNLOAD_DOWNLOAD_SHELF_H_
 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_SHELF_H_
 
-class DownloadItemModel;
+namespace content {
+class DownloadItem;
+}
+
 class Browser;
 
 // This is an abstract base class for platform specific download shelf
 // implementations.
 class DownloadShelf {
  public:
   DownloadShelf();
   virtual ~DownloadShelf() {}
 
-  // A new download has started, so add it to our shelf. This object will
-  // take ownership of |download_model|. Also make the shelf visible.
-  void AddDownload(DownloadItemModel* download_model);
+  // A new download has started, so add it to our shelf. Also make the shelf
+  // visible.
+  void AddDownload(content::DownloadItem* download);
 
   // The browser view needs to know when we are going away to properly return
   // the resize corner size to WebKit so that we don't draw on top of it.
   // This returns the showing state of our animation which is set to true at
   // the beginning Show and false at the beginning of a Hide.
   virtual bool IsShowing() const = 0;
 
   // Returns whether the download shelf is showing the close animation.
   virtual bool IsClosing() const = 0;
 
   // Opens the shelf.
   void Show();
 
   // Closes the shelf.
   void Close();
 
   // Hides the shelf. This closes the shelf if it is currently showing.
   void Hide();
 
   // Unhides the shelf. This will cause the shelf to be opened if it was open
   // when it was hidden, or was shown while it was hidden.
   void Unhide();
 
   virtual Browser* browser() const = 0;
 
   // Returns whether the download shelf is hidden.
   bool is_hidden() { return is_hidden_; }
 
  protected:
-  virtual void DoAddDownload(DownloadItemModel* download_model) = 0;
+  virtual void DoAddDownload(content::DownloadItem* download) = 0;
   virtual void DoShow() = 0;
   virtual void DoClose() = 0;
 
  private:
   bool should_show_on_unhide_;
   bool is_hidden_;
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_SHELF_H_