Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/base/file_flusher.cc

Index: chrome/browser/chromeos/base/file_flusher.cc
diff --git a/chrome/browser/chromeos/base/file_flusher.cc b/chrome/browser/chromeos/base/file_flusher.cc
index 406b66033c9af79f5ff3155856231cffdc61c7ff..9bf803c86b635200078dafa4106612489f0690ef 100644
--- a/chrome/browser/chromeos/base/file_flusher.cc
+++ b/chrome/browser/chromeos/base/file_flusher.cc
@@ -98,8 +98,7 @@ void FileFlusher::Job::Start() {
   }
 
   base::PostTaskWithTraitsAndReply(
-      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                     base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::Bind(&FileFlusher::Job::FlushAsync, base::Unretained(this)),
       base::Bind(&FileFlusher::Job::FinishOnUIThread, base::Unretained(this)));
 }