Remove SingleThreadTaskRunner Support from SchedulerWorkerPoolImpl

base/task_scheduler/priority_queue.cc

Index: base/task_scheduler/priority_queue.cc
diff --git a/base/task_scheduler/priority_queue.cc b/base/task_scheduler/priority_queue.cc
index cfe71ea897908c56001c0c6cd89d11d768d8da0f..fe03381219b6f21fcd9f7afd9a1b1daf388980cf 100644
--- a/base/task_scheduler/priority_queue.cc
+++ b/base/task_scheduler/priority_queue.cc
@@ -95,11 +95,6 @@ bool PriorityQueue::Transaction::IsEmpty() const {
 
 PriorityQueue::PriorityQueue() = default;
 
-PriorityQueue::PriorityQueue(const PriorityQueue* predecessor_priority_queue)
-    : container_lock_(&predecessor_priority_queue->container_lock_) {
-  DCHECK(predecessor_priority_queue);
-}
-
 PriorityQueue::~PriorityQueue() = default;
 
 std::unique_ptr<PriorityQueue::Transaction> PriorityQueue::BeginTransaction() {