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

content/browser/download/download_resource_handler.h

 // 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.
 
 #ifndef CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_
 #pragma once
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/timer.h"
 #include "content/browser/download/download_types.h"
 #include "content/browser/renderer_host/resource_handler.h"
+#include "content/public/browser/download_manager.h"
 #include "content/public/browser/download_id.h"
 #include "content/public/browser/global_request_id.h"
 #include "net/base/net_errors.h"
 
 class DownloadFileManager;
 class DownloadRequestHandle;
 class ResourceDispatcherHost;
 struct DownloadCreateInfo;
 
 namespace content {
 class DownloadBuffer;
 }
 
 namespace net {
 class URLRequest;
 }  // namespace net
 
 // Forwards data to the download thread.
 class DownloadResourceHandler : public ResourceHandler {
  public:
-  typedef base::Callback<void(content::DownloadId, net::Error)>
-      OnStartedCallback;
+  typedef content::DownloadManager::OnStartedCallback OnStartedCallback;
 
   static const size_t kLoadsToWrite = 100;  // number of data buffers queued
 
   // started_cb will be called exactly once on the UI thread.
   DownloadResourceHandler(ResourceDispatcherHost* rdh,
                           int render_process_host_id,
                           int render_view_id,
                           int request_id,
                           const GURL& url,
                           DownloadFileManager* download_file_manager,
@@ skipping 83 matching lines @@
   int64 bytes_read_;
   std::string accept_ranges_;
 
   static const int kReadBufSize = 32768;  // bytes
   static const int kThrottleTimeMs = 200;  // milliseconds
 
   DISALLOW_COPY_AND_ASSIGN(DownloadResourceHandler);
 };
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_