Add constexpr TaskTraits constructor.

base/BUILD.gn

 # Copyright (c) 2013 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.
 
 # HOW TO WRITE CONDITIONALS IN THIS FILE
 # ======================================
 #
 # In many other places, one would write a conditional that expresses all the
 # cases when a source file is used or unused, and then either add or subtract
 # it from the sources list in that case
@@ skipping 837 matching lines @@
     "task_scheduler/task_scheduler.cc",
     "task_scheduler/task_scheduler.h",
     "task_scheduler/task_scheduler_impl.cc",
     "task_scheduler/task_scheduler_impl.h",
     "task_scheduler/task_tracker.cc",
     "task_scheduler/task_tracker.h",
     "task_scheduler/task_tracker_posix.cc",
     "task_scheduler/task_tracker_posix.h",
     "task_scheduler/task_traits.cc",
     "task_scheduler/task_traits.h",
+    "task_scheduler/task_traits_details.h",
     "template_util.h",
     "test/malloc_wrapper.h",
     "third_party/dmg_fp/dmg_fp.h",
     "third_party/dmg_fp/dtoa_wrapper.cc",
     "third_party/dmg_fp/g_fmt.cc",
     "third_party/icu/icu_utf.cc",
     "third_party/icu/icu_utf.h",
     "third_party/nspr/prtime.cc",
     "third_party/nspr/prtime.h",
     "third_party/superfasthash/superfasthash.c",
@@ skipping 1241 matching lines @@
     "task_scheduler/scheduler_single_thread_task_runner_manager_unittest.cc",
     "task_scheduler/scheduler_worker_pool_impl_unittest.cc",
     "task_scheduler/scheduler_worker_stack_unittest.cc",
     "task_scheduler/scheduler_worker_unittest.cc",
     "task_scheduler/scoped_set_task_priority_for_current_thread_unittest.cc",
     "task_scheduler/sequence_sort_key_unittest.cc",
     "task_scheduler/sequence_unittest.cc",
     "task_scheduler/task_scheduler_impl_unittest.cc",
     "task_scheduler/task_tracker_posix_unittest.cc",
     "task_scheduler/task_tracker_unittest.cc",
+    "task_scheduler/task_traits_unittest.cc",
     "task_scheduler/task_unittest.cc",
     "task_scheduler/test_task_factory.cc",
     "task_scheduler/test_task_factory.h",
     "task_scheduler/test_utils.h",
     "template_util_unittest.cc",
     "test/histogram_tester_unittest.cc",
     "test/mock_callback_unittest.cc",
     "test/scoped_mock_time_message_loop_task_runner_unittest.cc",
     "test/scoped_task_scheduler_unittest.cc",
     "test/test_pending_task_unittest.cc",
@@ skipping 258 matching lines @@
 
 if (enable_nocompile_tests) {
   nocompile_test("base_nocompile_tests") {
     sources = [
       "bind_unittest.nc",
       "callback_list_unittest.nc",
       "callback_unittest.nc",
       "memory/ref_counted_unittest.nc",
       "memory/weak_ptr_unittest.nc",
       "metrics/histogram_unittest.nc",
+      "task_scheduler/task_traits_unittest.nc",
     ]
 
     deps = [
       ":base",
       "//base/test:run_all_unittests",
       "//testing/gtest",
     ]
   }
 }
 
@@ skipping 289 matching lines @@
 }
 
 fuzzer_test("base_json_correctness_fuzzer") {
   sources = [
     "json/correctness_fuzzer.cc",
   ]
   deps = [
     ":base",
   ]
 }