Exempt the Service Thread from BLOCK_SHUTDOWN DCHECKs

base/task_scheduler/task_scheduler_impl.cc

Index: base/task_scheduler/task_scheduler_impl.cc
diff --git a/base/task_scheduler/task_scheduler_impl.cc b/base/task_scheduler/task_scheduler_impl.cc
index e9ff513593a48f7d2640b03af7575e48da984f9f..8a85a1d7014402e26ff99f85b13a6b7fa1015af8 100644
--- a/base/task_scheduler/task_scheduler_impl.cc
+++ b/base/task_scheduler/task_scheduler_impl.cc
@@ -104,7 +104,11 @@ void TaskSchedulerImpl::Start(const TaskScheduler::InitParams& init_params) {
   // message_loop().
   task_tracker_.set_watch_file_descriptor_message_loop(
       static_cast<MessageLoopForIO*>(service_thread_.message_loop()));
-#endif
+
+#if DCHECK_IS_ON()
+  task_tracker_.set_service_thread_handle(service_thread_.GetThreadHandle());
+#endif  // DCHECK_IS_ON()
+#endif  // defined(OS_POSIX) && !defined(OS_NACL_SFI)
 
   // Needs to happen after starting the service thread to get its task_runner().
   delayed_task_manager_.Start(service_thread_.task_runner());