Revert "Fix a ton of compiler warnings."

chrome/browser/download/download_manager.h

Index: chrome/browser/download/download_manager.h
diff --git a/chrome/browser/download/download_manager.h b/chrome/browser/download/download_manager.h
index b7d87c7ccc1a9ec8acc9a48f98a756af6120694d..fec86ad3858bcbb38b76f5040e557026aebf5b61 100644
--- a/chrome/browser/download/download_manager.h
+++ b/chrome/browser/download/download_manager.h
@@ -98,9 +98,6 @@ class DownloadItem {
 
     // Called when a downloaded file has been opened.
     virtual void OnDownloadOpened(DownloadItem* download) = 0;
-
-   protected:
-    ~Observer() {}
   };
 
   // Constructing from persistent store:
@@ -326,9 +323,6 @@ class DownloadManager : public base::RefCountedThreadSafe<DownloadManager>,
     // 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