Use constexpr TaskTraits constructor in chrome.

chrome/browser/ui/webui/print_preview/print_preview_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/ui/webui/print_preview/print_preview_handler.h"
 
 #include <ctype.h>
 #include <stddef.h>
 
 #include <map>
@@ skipping 1372 matching lines @@
   DownloadPrefs* download_prefs = DownloadPrefs::FromBrowserContext(
       preview_web_contents()->GetBrowserContext());
   base::FilePath file_path = download_prefs->SaveFilePath();
   printing::StickySettings* sticky_settings = GetStickySettings();
   sticky_settings->SaveInPrefs(Profile::FromBrowserContext(
       preview_web_contents()->GetBrowserContext())->GetPrefs());
   // Handle the no prompting case. Like the dialog prompt, this function
   // returns and eventually FileSelected() gets called.
   if (!prompt_user) {
     base::PostTaskWithTraitsAndReplyWithResult(
-        FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                       base::TaskPriority::BACKGROUND),
+        FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
         base::Bind(&GetUniquePath,
                    download_prefs->SaveFilePath().Append(default_filename)),
         base::Bind(&PrintPreviewHandler::OnGotUniqueFileName,
                    weak_factory_.GetWeakPtr()));
     return;
   }
 
   // Otherwise prompt the user.
   ui::SelectFileDialog::FileTypeInfo file_type_info;
   file_type_info.extensions.resize(1);
@@ skipping 47 matching lines @@
 
 void PrintPreviewHandler::PostPrintToPdfTask() {
   scoped_refptr<base::RefCountedBytes> data;
   base::string16 title;
   if (!GetPreviewDataAndTitle(&data, &title)) {
     NOTREACHED() << "Preview data was checked before file dialog.";
     return;
   }
 
   base::PostTaskWithTraits(
-      FROM_HERE,
-      base::TaskTraits().MayBlock().WithPriority(
-          base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::BindOnce(&PrintToPdfCallback, data, print_to_pdf_path_,
                      pdf_file_saved_closure_));
   print_to_pdf_path_.clear();
   ClosePreviewDialog();
 }
 
 void PrintPreviewHandler::FileSelectionCanceled(void* params) {
   print_preview_ui()->OnFileSelectionCancelled();
 }
 
@@ skipping 304 matching lines @@
 
 void PrintPreviewHandler::UnregisterForGaiaCookieChanges() {
   if (gaia_cookie_manager_service_)
     gaia_cookie_manager_service_->RemoveObserver(this);
 }
 
 void PrintPreviewHandler::SetPdfSavedClosureForTesting(
     const base::Closure& closure) {
   pdf_file_saved_closure_ = closure;
 }