Implemented ExternalData interface on DownloadItem and used it for SafeBrowsing.

chrome/browser/download/chrome_download_manager_delegate.h

 // Copyright (c) 2011 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_CHROME_DOWNLOAD_MANAGER_DELEGATE_H_
 #define CHROME_BROWSER_DOWNLOAD_CHROME_DOWNLOAD_MANAGER_DELEGATE_H_
 #pragma once
 
 #include "base/compiler_specific.h"
 #include "base/hash_tables.h"
@@ skipping 127 matching lines @@
   void OnItemAddedToPersistentStore(int32 download_id, int64 db_handle);
 
   Profile* profile_;
   scoped_ptr<DownloadPrefs> download_prefs_;
   scoped_ptr<DownloadHistory> download_history_;
 
   // Maps from pending extension installations to DownloadItem IDs.
   typedef base::hash_map<CrxInstaller*, int> CrxInstallerMap;
   CrxInstallerMap crx_installers_;
 
-  // Maps the SafeBrowsing download check state to a DownloadItem ID.
-  struct SafeBrowsingState {
-    // If true the SafeBrowsing check is not done yet.
-    bool pending;
-    // The verdict that we got from calling CheckClientDownload.
-    safe_browsing::DownloadProtectionService::DownloadCheckResult verdict;
-  };
-  typedef base::hash_map<int, SafeBrowsingState> SafeBrowsingStateMap;
-  SafeBrowsingStateMap safe_browsing_state_;
-
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeDownloadManagerDelegate);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_CHROME_DOWNLOAD_MANAGER_DELEGATE_H_