Downloads: replace BrowserThread::FILE with task scheduler.

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/browser/download/download_task_runner.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/log/net_log_with_source.h"
 
 namespace content {
 
 // 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 don't always
 //               have access to the SavePackage at this point.
 SaveFile::SaveFile(const SaveFileCreateInfo* info, bool calculate_hash)
     : file_(net::NetLogWithSource()), info_(info) {
-  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+  DCHECK(GetDownloadTaskRunner()->RunsTasksInCurrentSequence());
 
   DCHECK(info);
   DCHECK(info->path.empty());
 }
 
 SaveFile::~SaveFile() {
-  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+  DCHECK(GetDownloadTaskRunner()->RunsTasksInCurrentSequence());
 }
 
 DownloadInterruptReason SaveFile::Initialize() {
   return file_.Initialize(base::FilePath(), base::FilePath(), base::File(), 0,
                           std::string(), std::unique_ptr<crypto::SecureHash>(),
                           false);
 }
 
 DownloadInterruptReason SaveFile::AppendDataToFile(const char* data,
                                                    size_t data_len) {
@@ skipping 32 matching lines @@
 
 int64_t SaveFile::BytesSoFar() const {
   return file_.bytes_so_far();
 }
 
 std::string SaveFile::DebugString() const {
   return file_.DebugString();
 }
 
 }  // namespace content