Add constexpr TaskTraits constructor.

base/task_scheduler/task_scheduler_impl_unittest.cc

Index: base/task_scheduler/task_scheduler_impl_unittest.cc
diff --git a/base/task_scheduler/task_scheduler_impl_unittest.cc b/base/task_scheduler/task_scheduler_impl_unittest.cc
index b8d8fad8343808296bff8dd7acedba946bdf8e4e..2f6ba8198d2998f43cf99bd060fb2db2a870caad 100644
--- a/base/task_scheduler/task_scheduler_impl_unittest.cc
+++ b/base/task_scheduler/task_scheduler_impl_unittest.cc
@@ -141,7 +141,7 @@ class ThreadPostingTasks : public SimpleThread {
     const size_t kNumTasksPerThread = 150;
     for (size_t i = 0; i < kNumTasksPerThread; ++i) {
       factory_.PostTask(test::TestTaskFactory::PostNestedTask::NO,
-                        Bind(&VerifyTaskEnvironment, traits_));
+                        Bind(&VerifyTaskEnvironment, ConstRef(traits_)));
     }
   }
 
@@ -219,8 +219,8 @@ TEST_P(TaskSchedulerImplTest, PostDelayedTaskWithTraitsNoDelay) {
                          WaitableEvent::InitialState::NOT_SIGNALED);
   scheduler_.PostDelayedTaskWithTraits(
       FROM_HERE, GetParam().traits,
-      BindOnce(&VerifyTaskEnvironmentAndSignalEvent, GetParam().traits,
-               Unretained(&task_ran)),
+      BindOnce(&VerifyTaskEnvironmentAndSignalEvent,
+               ConstRef(GetParam().traits), Unretained(&task_ran)),
       TimeDelta());
   task_ran.Wait();
 }
@@ -235,7 +235,8 @@ TEST_P(TaskSchedulerImplTest, PostDelayedTaskWithTraitsWithDelay) {
                          WaitableEvent::InitialState::NOT_SIGNALED);
   scheduler_.PostDelayedTaskWithTraits(
       FROM_HERE, GetParam().traits,
-      BindOnce(&VerifyTimeAndTaskEnvironmentAndSignalEvent, GetParam().traits,
+      BindOnce(&VerifyTimeAndTaskEnvironmentAndSignalEvent,
+               ConstRef(GetParam().traits),
                TimeTicks::Now() + TestTimeouts::tiny_timeout(),
                Unretained(&task_ran)),
       TestTimeouts::tiny_timeout());
@@ -256,7 +257,7 @@ TEST_P(TaskSchedulerImplTest, PostTasksViaTaskRunner) {
   const size_t kNumTasksPerTest = 150;
   for (size_t i = 0; i < kNumTasksPerTest; ++i) {
     factory.PostTask(test::TestTaskFactory::PostNestedTask::NO,
-                     Bind(&VerifyTaskEnvironment, GetParam().traits));
+                     Bind(&VerifyTaskEnvironment, ConstRef(GetParam().traits)));
   }
 
   factory.WaitForAllTasksToRun();
@@ -269,8 +270,8 @@ TEST_P(TaskSchedulerImplTest, PostDelayedTaskWithTraitsNoDelayBeforeStart) {
                              WaitableEvent::InitialState::NOT_SIGNALED);
   scheduler_.PostDelayedTaskWithTraits(
       FROM_HERE, GetParam().traits,
-      BindOnce(&VerifyTaskEnvironmentAndSignalEvent, GetParam().traits,
-               Unretained(&task_running)),
+      BindOnce(&VerifyTaskEnvironmentAndSignalEvent,
+               ConstRef(GetParam().traits), Unretained(&task_running)),
       TimeDelta());
 
   // Wait a little bit to make sure that the task isn't scheduled before
@@ -291,7 +292,8 @@ TEST_P(TaskSchedulerImplTest, PostDelayedTaskWithTraitsWithDelayBeforeStart) {
                              WaitableEvent::InitialState::NOT_SIGNALED);
   scheduler_.PostDelayedTaskWithTraits(
       FROM_HERE, GetParam().traits,
-      BindOnce(&VerifyTimeAndTaskEnvironmentAndSignalEvent, GetParam().traits,
+      BindOnce(&VerifyTimeAndTaskEnvironmentAndSignalEvent,
+               ConstRef(GetParam().traits),
                TimeTicks::Now() + TestTimeouts::tiny_timeout(),
                Unretained(&task_running)),
       TestTimeouts::tiny_timeout());
@@ -314,9 +316,9 @@ TEST_P(TaskSchedulerImplTest, PostTaskViaTaskRunnerBeforeStart) {
                              WaitableEvent::InitialState::NOT_SIGNALED);
   CreateTaskRunnerWithTraitsAndExecutionMode(&scheduler_, GetParam().traits,
                                              GetParam().execution_mode)
-      ->PostTask(FROM_HERE,
-                 BindOnce(&VerifyTaskEnvironmentAndSignalEvent,
-                          GetParam().traits, Unretained(&task_running)));
+      ->PostTask(FROM_HERE, BindOnce(&VerifyTaskEnvironmentAndSignalEvent,
+                                     ConstRef(GetParam().traits),
+                                     Unretained(&task_running)));
 
   // Wait a little bit to make sure that the task isn't scheduled before
   // Start(). Note: This test won't catch a case where the task runs just after