Revert "Fix a ton of compiler warnings."

chrome/browser/download/download_manager.h

 // Copyright (c) 2006-2009 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.
 //
 // The DownloadManager object manages the process of downloading, including
 // updates to the history system and providing the information for displaying
 // the downloads view in the Destinations tab. There is one DownloadManager per
 // active profile in Chrome.
 //
 // Each download is represented by a DownloadItem, and all DownloadItems
@@ skipping 80 matching lines @@
   };
 
   // Interface that observers of a particular download must implement in order
   // to receive updates to the download's status.
   class Observer {
    public:
     virtual void OnDownloadUpdated(DownloadItem* download) = 0;
 
     // Called when a downloaded file has been opened.
     virtual void OnDownloadOpened(DownloadItem* download) = 0;
-
-   protected:
-    ~Observer() {}
   };
 
   // Constructing from persistent store:
   DownloadItem(const DownloadCreateInfo& info);
 
   // Constructing from user action:
   DownloadItem(int32 download_id,
                const FilePath& path,
                int path_uniquifier,
                const GURL& url,
@@ skipping 205 matching lines @@
   class Observer {
    public:
     // New or deleted download, observers should query us for the current set
     // of downloads.
     virtual void ModelChanged() = 0;
 
     // A callback once the DownloadManager has retrieved the requested set of
     // downloads. The DownloadManagerObserver must copy the vector, but does not
     // own the individual DownloadItems, when this call is made.
     virtual void SetDownloads(std::vector<DownloadItem*>& downloads) = 0;
-
-   protected:
-    ~Observer() {}
   };
 
   // Public API
 
   // Begin a search for all downloads matching 'search_text'. If 'search_text'
   // is empty, return all known downloads. The results are returned in the
   // 'SetDownloads' observer callback.
   void GetDownloads(Observer* observer,
                     const std::wstring& search_text);
 
@@ skipping 278 matching lines @@
   PendingFinishedMap pending_finished_downloads_;
 
   // The "Save As" dialog box used to ask the user where a file should be
   // saved.
   scoped_refptr<SelectFileDialog> select_file_dialog_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadManager);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_MANAGER_H_