Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/system_logs/debug_daemon_log_source.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/system_logs/debug_daemon_log_source.h"
 
 #include <stddef.h>
 
 #include <memory>
 
@@ skipping 134 matching lines @@
          it != users.end();
          ++it) {
       if ((*it)->username_hash().empty())
         continue;
       profile_dirs.push_back(
           chromeos::ProfileHelper::GetProfilePathByUserIdHash(
               (*it)->username_hash()));
     }
 
     base::PostTaskWithTraitsAndReply(
-        FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                       base::TaskPriority::BACKGROUND),
+        FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
         base::Bind(&DebugDaemonLogSource::ReadUserLogFiles, user_log_files,
                    profile_dirs, response),
         base::Bind(&DebugDaemonLogSource::MergeResponse,
                    weak_ptr_factory_.GetWeakPtr(), base::Owned(response)));
   } else {
     (*response_)[kUserLogFileKeyName] = kNotAvailable;
     RequestCompleted();
   }
 }
 
@@ skipping 32 matching lines @@
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   DCHECK(!callback_.is_null());
 
   --num_pending_requests_;
   if (num_pending_requests_ > 0)
     return;
   callback_.Run(response_.get());
 }
 
 }  // namespace system_logs