Use constexpr TaskTraits constructor in base.

Use a constexpr constructor that accepts traits in any order instead of
the builder pattern to construct TaskTraits in base.

BUG=713683
R=gab@chromium.org

Review-Url: https://codereview.chromium.org/2861833002
Cr-Commit-Position: refs/heads/master@{#469167}


CrOS-Libchrome-Original-Commit: 2524b542c3053e57d0c70593d26c86ef4785f881
diff --git a/base/test/scoped_task_scheduler.h b/base/test/scoped_task_scheduler.h
index 7854439..010b39e 100644
--- a/base/test/scoped_task_scheduler.h
+++ b/base/test/scoped_task_scheduler.h
@@ -41,8 +41,7 @@
 // base::PostTask(FROM_HERE, base::Bind(&RunLoop::Quit, &run_loop));
 // base::PostTask(FROM_HERE, base::Bind(&C));
 // base::PostTaskWithTraits(
-//     base::TaskTraits().WithShutdownBehavior(
-//         base::TaskShutdownBehavior::BLOCK_SHUTDOWN),
+//     {base::TaskShutdownBehavior::BLOCK_SHUTDOWN},
 //     base::Bind(&D));
 // run_loop.Run();  // Returns after running B and RunLoop::Quit.
 //
diff --git a/base/trace_event/trace_log.cc b/base/trace_event/trace_log.cc
index d1e0fc3..b6570fd 100644
--- a/base/trace_event/trace_log.cc
+++ b/base/trace_event/trace_log.cc
@@ -971,11 +971,8 @@
   if (use_worker_thread_) {
     base::PostTaskWithTraits(
         FROM_HERE,
-        base::TaskTraits()
-            .MayBlock()
-            .WithPriority(base::TaskPriority::BACKGROUND)
-            .WithShutdownBehavior(
-                base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN),
+        {MayBlock(), TaskPriority::BACKGROUND,
+         TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
         BindOnce(&TraceLog::ConvertTraceEventsToTraceFormat,
                  Passed(&previous_logged_events), flush_output_callback,
                  argument_filter_predicate));