Do not inherit TaskPriority in TaskTraits.

base/task_scheduler/task_traits.cc

 // Copyright 2016 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 "base/task_scheduler/task_traits.h"
 
 #include <stddef.h>
 
 #include <ostream>
 
 #include "base/logging.h"
-#include "base/task_scheduler/scoped_set_task_priority_for_current_thread.h"
 
 namespace base {
 
-// Do not rely on defaults hard-coded below beyond the guarantees described in
-// the header; anything else is subject to change. Tasks should explicitly
-// request defaults if the behavior is critical to the task.
-TaskTraits::TaskTraits()
-    : may_block_(false),
-      with_base_sync_primitives_(false),
-      priority_(internal::GetTaskPriorityForCurrentThread()),
-      shutdown_behavior_(TaskShutdownBehavior::SKIP_ON_SHUTDOWN) {}
-
+TaskTraits::TaskTraits() = default;
 TaskTraits::~TaskTraits() = default;
 
 TaskTraits& TaskTraits::MayBlock() {
   may_block_ = true;
   return *this;
 }
 
 TaskTraits& TaskTraits::WithBaseSyncPrimitives() {
   with_base_sync_primitives_ = true;
   return *this;
 }
 
 TaskTraits& TaskTraits::WithPriority(TaskPriority priority) {
+  priority_set_explicitly_ = true;
   priority_ = priority;
   return *this;
 }
 
 TaskTraits& TaskTraits::WithShutdownBehavior(
     TaskShutdownBehavior shutdown_behavior) {
   shutdown_behavior_ = shutdown_behavior;
   return *this;
 }
 
@@ skipping 29 matching lines @@
   return os;
 }
 
 std::ostream& operator<<(std::ostream& os,
                          const TaskShutdownBehavior& shutdown_behavior) {
   os << TaskShutdownBehaviorToString(shutdown_behavior);
   return os;
 }
 
 }  // namespace base