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

services/shell/standalone/context.cc

Index: services/shell/standalone/context.cc
diff --git a/services/shell/standalone/context.cc b/services/shell/standalone/context.cc
index 47565d6a3247a974e0a4fddcf51545e9b2ece095..9e66b6697b3047788a771b77a42fc927e9dae576 100644
--- a/services/shell/standalone/context.cc
+++ b/services/shell/standalone/context.cc
@@ -138,7 +138,8 @@ void Context::Init(std::unique_ptr<InitParams> init_params) {
 
   shell_runner_ = base::ThreadTaskRunnerHandle::Get();
   blocking_pool_ =
-      new base::SequencedWorkerPool(kMaxBlockingPoolThreads, "blocking_pool");
+      new base::SequencedWorkerPool(kMaxBlockingPoolThreads, "blocking_pool",
+                                    base::TaskPriority::USER_VISIBLE);
 
   init_edk_ = !init_params || init_params->init_edk;
   if (init_edk_) {