Add TaskPriority as a parameter to SequencedWorkerPool in preparation for TaskScheduler experiment.

ash/sysui/sysui_application.cc

Index: ash/sysui/sysui_application.cc
diff --git a/ash/sysui/sysui_application.cc b/ash/sysui/sysui_application.cc
index adef771280809d6a02ee90bd0f3acbd63f09ea08..345efb01788aa8c8c38874aa14b3b56e37bbe2cc 100644
--- a/ash/sysui/sysui_application.cc
+++ b/ash/sysui/sysui_application.cc
@@ -205,7 +205,11 @@ class NativeWidgetFactory {
 
 class AshInit {
  public:
-  AshInit() : worker_pool_(new base::SequencedWorkerPool(2, "AshWorkerPool")) {
+  AshInit()
+      : worker_pool_(
+            new base::SequencedWorkerPool(2,
+                                          "AshWorkerPool",
+                                          base::TaskPriority::USER_BLOCKING)) {
     ui::RegisterPathProvider();
   }