Make the UI an observer of downloads.

content/browser/download/download_manager_impl.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 CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_MANAGER_IMPL_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_MANAGER_IMPL_H_
 
 #include <map>
 #include <set>
 
@@ skipping 111 matching lines @@
       DownloadItemImpl* item, const DownloadTargetCallback& callback) OVERRIDE;
   virtual void ReadyForDownloadCompletion(
       DownloadItemImpl* item, const base::Closure& complete_callback) OVERRIDE;
   virtual bool ShouldOpenFileBasedOnExtension(const FilePath& path) OVERRIDE;
   virtual bool ShouldOpenDownload(
       DownloadItemImpl* item,
       const ShouldOpenDownloadCallback& callback) OVERRIDE;
   virtual void CheckForFileRemoval(DownloadItemImpl* download_item) OVERRIDE;
   virtual void DownloadOpened(DownloadItemImpl* download) OVERRIDE;
   virtual void DownloadRemoved(DownloadItemImpl* download) OVERRIDE;
-  virtual void ShowDownloadInBrowser(DownloadItemImpl* download) OVERRIDE;
 
   // Factory for creation of downloads items.
   scoped_ptr<DownloadItemFactory> item_factory_;
 
   // Factory for the creation of download files.
   scoped_ptr<DownloadFileFactory> file_factory_;
 
   // |downloads_| is the owning set for all downloads known to the
   // DownloadManager.  This includes downloads started by the user in
   // this session, downloads initialized from the history system, and
@@ skipping 15 matching lines @@
   DownloadManagerDelegate* delegate_;
 
   net::NetLog* net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadManagerImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_MANAGER_IMPL_H_