Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/drive/download_handler.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 "chrome/browser/chromeos/drive/download_handler.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
@@ skipping 364 matching lines @@
       NOTREACHED();
   }
 }
 
 void DownloadHandler::OnCreateDirectory(
     const SubstituteDriveDownloadPathCallback& callback,
     FileError error) {
   DVLOG(1) << "OnCreateDirectory " << FileErrorToString(error);
   if (error == FILE_ERROR_OK) {
     base::PostTaskWithTraitsAndReplyWithResult(
-        FROM_HERE, base::TaskTraits().MayBlock(),
+        FROM_HERE, {base::MayBlock()},
         base::Bind(&GetDriveTempDownloadPath, drive_tmp_download_path_),
         callback);
   } else {
     LOG(WARNING) << "Failed to create directory, error = "
                  << FileErrorToString(error);
     callback.Run(base::FilePath());
   }
 }
 
 void DownloadHandler::UploadDownloadItem(DownloadManager* manager,
@@ skipping 30 matching lines @@
 
 DownloadManager* DownloadHandler::GetDownloadManager(void* manager_id) {
   if (manager_id == notifier_->GetManager())
     return notifier_->GetManager();
   if (notifier_incognito_ && manager_id == notifier_incognito_->GetManager())
     return notifier_incognito_->GetManager();
   return NULL;
 }
 
 }  // namespace drive