Don't leak ChromeDownloadManagerDelegate in DownloadService

chrome/browser/download/download_service.cc

 // 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.
 
 #include "chrome/browser/download/download_service.h"
 
 #include "base/callback.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/download/chrome_download_manager_delegate.h"
 #include "chrome/browser/download/download_service_factory.h"
@@ skipping 89 matching lines @@
 
 void DownloadService::Shutdown() {
   if (download_manager_created_) {
     // Normally the DownloadManager would be shutdown later, after the Profile
     // goes away and BrowserContext's destructor runs. But that would be too
     // late for us since we need to use the profile (indirectly through history
     // code) when the DownloadManager is shutting down. So we shut it down
     // manually earlier. See http://crbug.com/131692
     BrowserContext::GetDownloadManager(profile_)->Shutdown();
   }
-  manager_delegate_.release();
+  manager_delegate_ = NULL;
 }