Added callback to DownloadUrl() so we can find download failures.

content/browser/tab_contents/tab_contents.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 "content/browser/tab_contents/tab_contents.h"
 
 #include <cmath>
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
@@ skipping 2448 matching lines @@
       post_id = entry->GetPostID();
   }
   DownloadSaveInfo save_info;
   save_info.prompt_for_save_location = true;
   dlm->DownloadUrl(url,
                    referrer,
                    "",
                    true,  // prefer_cache
                    post_id,
                    save_info,
-                   this);
+                   this,
+                   DownloadManager::OnStartedCallback());
 }
 
 void TabContents::CreateViewAndSetSizeForRVH(RenderViewHost* rvh) {
   RenderWidgetHostView* rwh_view = GetView()->CreateViewForWidget(rvh);
   // Can be NULL during tests.
   if (rwh_view)
     rwh_view->SetSize(GetView()->GetContainerSize());
 }