Use the user's preferred downloads directory for creating the initial download file.

content/browser/download/download_file_impl.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/download/download_file_impl.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/file_util.h"
@@ skipping 27 matching lines @@
         : file_(info->save_info.file_path,
                 info->url(),
                 info->referrer_url,
                 info->received_bytes,
                 calculate_hash,
                 info->save_info.hash_state,
                 info->save_info.file_stream,
                 bound_net_log),
           stream_reader_(stream.Pass()),
           id_(info->download_id),
+          default_download_directory_(info->default_download_directory),
           request_handle_(request_handle),
           download_manager_(download_manager),
           bytes_seen_(0),
           bound_net_log_(bound_net_log),
           weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)),
           power_save_blocker_(power_save_blocker.Pass()) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   DCHECK(download_manager.get());
 }
 
 DownloadFileImpl::~DownloadFileImpl() {
 }
 
 content::DownloadInterruptReason DownloadFileImpl::Initialize() {
   update_timer_.reset(new base::RepeatingTimer<DownloadFileImpl>());
-  net::Error result = file_.Initialize();
+  net::Error result = file_.Initialize(default_download_directory_);
   if (result != net::OK) {
     return content::ConvertNetErrorToInterruptReason(
         result, content::DOWNLOAD_INTERRUPT_FROM_DISK);
   }
 
   stream_reader_->RegisterCallback(
       base::Bind(&DownloadFileImpl::StreamActive, weak_factory_.GetWeakPtr()));
 
   download_start_ = base::TimeTicks::Now();
   // Initial pull from the straw.
@@ skipping 220 matching lines @@
   }
 }
 
 void DownloadFileImpl::SendUpdate() {
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&DownloadManager::UpdateDownload,
                  download_manager_, id_.local(),
                  BytesSoFar(), CurrentSpeed(), GetHashState()));
 }