Do not inherit TaskPriority in TaskTraits.

base/task_scheduler/task_traits_unittest.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 "base/task_scheduler/scoped_set_task_priority_for_current_thread.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-namespace base {
-
-// Verify that TaskTraits is initialized with the priority of the task running
-// on the current thread.
-TEST(TaskSchedulerTaskTraitsTest, DefaultPriority) {
-  {
-    internal::ScopedSetTaskPriorityForCurrentThread scope(
-        TaskPriority::BACKGROUND);
-    EXPECT_EQ(TaskPriority::BACKGROUND, TaskTraits().priority());
-  }
-  {
-    internal::ScopedSetTaskPriorityForCurrentThread scope(
-        TaskPriority::USER_VISIBLE);
-    EXPECT_EQ(TaskPriority::USER_VISIBLE, TaskTraits().priority());
-  }
-  {
-    internal::ScopedSetTaskPriorityForCurrentThread scope(
-        TaskPriority::USER_BLOCKING);
-    EXPECT_EQ(TaskPriority::USER_BLOCKING, TaskTraits().priority());
-  }
-}
-
-}  // namespace base