TaskScheduler: Add TaskTraits::WithWait().

base/task_scheduler/task_tracker.cc

Index: base/task_scheduler/task_tracker.cc
diff --git a/base/task_scheduler/task_tracker.cc b/base/task_scheduler/task_tracker.cc
index 49a33be8c24b113f82c0ab0a1ad1047465aee2bb..2ab4a4eff277c35e6fc2c86f8d59c25e920cb2fa 100644
--- a/base/task_scheduler/task_tracker.cc
+++ b/base/task_scheduler/task_tracker.cc
@@ -225,6 +225,8 @@ bool TaskTracker::RunTask(std::unique_ptr<Task> task,
             TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN);
     const bool previous_io_allowed =
         ThreadRestrictions::SetIOAllowed(task->traits.with_file_io());
+    const bool previous_wait_allowed =
+        ThreadRestrictions::SetWaitAllowed(task->traits.with_wait());
 
     {
       // Set up SequenceToken as expected for the scope of the task.
@@ -261,8 +263,9 @@ bool TaskTracker::RunTask(std::unique_ptr<Task> task,
       PerformRunTask(std::move(task));
     }
 
-    ThreadRestrictions::SetSingletonAllowed(previous_singleton_allowed);
+    ThreadRestrictions::SetWaitAllowed(previous_wait_allowed);
     ThreadRestrictions::SetIOAllowed(previous_io_allowed);
+    ThreadRestrictions::SetSingletonAllowed(previous_singleton_allowed);
 
     AfterRunTask(shutdown_behavior);
   }