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

services/shell/runner/host/child_process_host_unittest.cc

Index: services/shell/runner/host/child_process_host_unittest.cc
diff --git a/services/shell/runner/host/child_process_host_unittest.cc b/services/shell/runner/host/child_process_host_unittest.cc
index f4867d4e754ac2c0a1792308273322ea9e61c498..cd84ba7c607b16fa41d6aa8b36fe9ed316abe6bc 100644
--- a/services/shell/runner/host/child_process_host_unittest.cc
+++ b/services/shell/runner/host/child_process_host_unittest.cc
@@ -78,7 +78,8 @@ TEST(ChildProcessHostTest, MAYBE_StartJoin) {
   PathService::Get(base::DIR_MODULE, &shell_dir);
   base::MessageLoop message_loop;
   scoped_refptr<base::SequencedWorkerPool> blocking_pool(
-      new base::SequencedWorkerPool(3, "blocking_pool"));
+      new base::SequencedWorkerPool(3, "blocking_pool",
+                                    base::TaskPriority::USER_VISIBLE));
 
   base::Thread io_thread("io_thread");
   base::Thread::Options options;