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

net/ssl/ssl_platform_key_task_runner.cc

Index: net/ssl/ssl_platform_key_task_runner.cc
diff --git a/net/ssl/ssl_platform_key_task_runner.cc b/net/ssl/ssl_platform_key_task_runner.cc
index 7611d60454dccbef7f7ea8f1915e3c124511ebf8..04f9e726f8c3703e19e20d3e3d158d7203fa54d2 100644
--- a/net/ssl/ssl_platform_key_task_runner.cc
+++ b/net/ssl/ssl_platform_key_task_runner.cc
@@ -8,7 +8,8 @@
 namespace net {
 
 SSLPlatformKeyTaskRunner::SSLPlatformKeyTaskRunner() {
-  worker_pool_ = new base::SequencedWorkerPool(1, "Platform Key Thread");
+  worker_pool_ = new base::SequencedWorkerPool(
+      1, "Platform Key Thread", base::TaskPriority::USER_BLOCKING);
   task_runner_ = worker_pool_->GetSequencedTaskRunnerWithShutdownBehavior(
       worker_pool_->GetSequenceToken(),
       base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);