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

content/browser/download/save_file.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_file.h"
 
 #include "base/logging.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/content_browser_client.h"
 #include "net/base/file_stream.h"
 
 using content::BrowserThread;
 
+// TODO(asanka): SaveFile should use the target directory of the save package as
+//               the default download directory when initializing |file_|.
+//               Unfortunately, as it is, constructors of SaveFile doesn't
+//               always have access to the SavePackage at this point.
 SaveFile::SaveFile(const SaveFileCreateInfo* info, bool calculate_hash)
-    : file_(FilePath(),
+    : file_(content::GetContentClient()->browser()->
+                GetDefaultDownloadDirectory(),

[Randy Smith (Not in Mondays), 2012/09/14 16:38:16]

Is this safe to access on the file thread?

[asanka, 2012/09/14 19:11:45]

It's documented as "can be called on any thread."

+            FilePath(),
             info->url,
             GURL(),
             0,
             calculate_hash,
             "",
             linked_ptr<net::FileStream>(),
             net::BoundNetLog()),
       info_(info) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 
@@ skipping 45 matching lines @@
   return file_.bytes_so_far();
 }
 
 bool SaveFile::GetHash(std::string* hash) {
   return file_.GetHash(hash);
 }
 
 std::string SaveFile::DebugString() const {
   return file_.DebugString();
 }