Add base::TaskTraits::Override().

base/task_scheduler/post_task.cc

Index: base/task_scheduler/post_task.cc
diff --git a/base/task_scheduler/post_task.cc b/base/task_scheduler/post_task.cc
index 6da11bd8dc15061bc6f0d23536b6df945c379adf..ec4bfb50f2dd8572f494e521a76ef3794daac9a5 100644
--- a/base/task_scheduler/post_task.cc
+++ b/base/task_scheduler/post_task.cc
@@ -34,10 +34,10 @@ class PostTaskAndReplyTaskRunner : public internal::PostTaskAndReplyImpl {
 // explicitly in |traits|, the returned TaskTraits have the current
 // TaskPriority.
 TaskTraits GetTaskTraitsWithExplicitPriority(const TaskTraits& traits) {
-  return traits.priority_set_explicitly()
-             ? traits
-             : TaskTraits(traits).WithPriority(
-                   internal::GetTaskPriorityForCurrentThread());
+  if (traits.priority_set_explicitly())
+    return traits;
+  return TaskTraits::Override(traits,
+                              {internal::GetTaskPriorityForCurrentThread()});
 }
 
 }  // namespace