Use constexpr TaskTraits constructor in chrome.

chrome/browser/download/notification/download_item_notification.cc

Index: chrome/browser/download/notification/download_item_notification.cc
diff --git a/chrome/browser/download/notification/download_item_notification.cc b/chrome/browser/download/notification/download_item_notification.cc
index d0b23948508270e57142cde695a21053d7bee2b3..d80905bf53cf1b653417bcbbc3377d10dc01170d 100644
--- a/chrome/browser/download/notification/download_item_notification.cc
+++ b/chrome/browser/download/notification/download_item_notification.cc
@@ -482,8 +482,7 @@ void DownloadItemNotification::UpdateNotificationData(
     if (model.HasSupportedImageMimeType()) {
       base::FilePath file_path = item_->GetFullPath();
       base::PostTaskWithTraitsAndReplyWithResult(
-          FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                         base::TaskPriority::BACKGROUND),
+          FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
           base::Bind(&ReadNotificationImage, file_path),
           base::Bind(&DownloadItemNotification::OnImageLoaded,
                      weak_factory_.GetWeakPtr()));
@@ -593,8 +592,7 @@ void DownloadItemNotification::OnImageDecoded(const SkBitmap& decoded_bitmap) {
   }
 
   base::PostTaskWithTraitsAndReplyWithResult(
-      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                     base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::Bind(&CropImage, decoded_bitmap),
       base::Bind(&DownloadItemNotification::OnImageCropped,
                  weak_factory_.GetWeakPtr()));