Reland DownloadItem::Observer::OnDownloadDestroyed() replaces DownloadItem::REMOVING

chrome/browser/ui/cocoa/download/download_item_mac.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_UI_COCOA_DOWNLOAD_DOWNLOAD_ITEM_MAC_H_
 #define CHROME_BROWSER_UI_COCOA_DOWNLOAD_DOWNLOAD_ITEM_MAC_H_
 #pragma once
 
 #import <Cocoa/Cocoa.h>
 
@@ skipping 20 matching lines @@
   // DownloadItemMac takes ownership of |download_model|.
   DownloadItemMac(BaseDownloadItemModel* download_model,
                   DownloadItemController* controller);
 
   // Destructor.
   virtual ~DownloadItemMac();
 
   // content::DownloadItem::Observer implementation
   virtual void OnDownloadUpdated(content::DownloadItem* download) OVERRIDE;
   virtual void OnDownloadOpened(content::DownloadItem* download) OVERRIDE;
+  virtual void OnDownloadDestroyed(content::DownloadItem* download) OVERRIDE;
 
   BaseDownloadItemModel* download_model() { return download_model_.get(); }
 
   // Asynchronous icon loading support.
   void LoadIcon();
 
  private:
   // Callback for asynchronous icon loading.
   void OnExtractIconComplete(IconManager::Handle handle,
                              gfx::Image* icon_bitmap);
 
   // The download item model we represent.
   scoped_ptr<BaseDownloadItemModel> download_model_;
 
   // The objective-c controller object.
   DownloadItemController* item_controller_;  // weak, owns us.
 
   // For canceling an in progress icon request.
   CancelableRequestConsumerT<int, 0> icon_consumer_;
 
   // Stores the last known path where the file will be saved.
   FilePath lastFilePath_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadItemMac);
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_DOWNLOAD_DOWNLOAD_ITEM_MAC_H_