Remove SingleThreadTaskRunner Support from SchedulerWorkerPoolImpl

base/task_scheduler/priority_queue.h

Index: base/task_scheduler/priority_queue.h
diff --git a/base/task_scheduler/priority_queue.h b/base/task_scheduler/priority_queue.h
index 887579377af4e8a72e94fe683362d8d5c22df8c8..2844ef3fa5442a9b7ba93b15c72626f46e187a83 100644
--- a/base/task_scheduler/priority_queue.h
+++ b/base/task_scheduler/priority_queue.h
@@ -70,11 +70,6 @@ class BASE_EXPORT PriorityQueue {
 
   PriorityQueue();
 
-  // |predecessor_priority_queue| is a PriorityQueue for which a thread is
-  // allowed to have an active Transaction when it creates a Transaction for
-  // this PriorityQueue.
-  PriorityQueue(const PriorityQueue* predecessor_priority_queue);
-
   ~PriorityQueue();
 
   // Begins a Transaction. This method cannot be called on a thread which has an