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

content/browser/download/save_package.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/save_package.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/file_path.h"
@@ skipping 1225 matching lines @@
 }
 
 void SavePackage::GetSaveInfo() {
   // Can't use web_contents_ in the file thread, so get the data that we need
   // before calling to it.
   FilePath website_save_dir, download_save_dir;
   bool skip_dir_check;
   DCHECK(download_manager_);
   if (download_manager_->GetDelegate()) {
     download_manager_->GetDelegate()->GetSaveDir(
-        web_contents(), &website_save_dir, &download_save_dir, &skip_dir_check);
+        web_contents()->GetBrowserContext(), &website_save_dir,
+        &download_save_dir, &skip_dir_check);
   }
   std::string mime_type = web_contents()->GetContentsMimeType();
   std::string accept_languages =
       content::GetContentClient()->browser()->GetAcceptLangs(
           web_contents()->GetBrowserContext());
 
   BrowserThread::PostTask(
       BrowserThread::FILE, FROM_HERE,
       base::Bind(&SavePackage::CreateDirectoryOnFileThread, this,
           website_save_dir, download_save_dir, skip_dir_check,
@@ skipping 104 matching lines @@
   StopObservation();
 }
 
 void SavePackage::FinalizeDownloadEntry() {
   DCHECK(download_);
   DCHECK(download_manager_);
 
   download_manager_->SavePageDownloadFinished(download_);
   StopObservation();
 }