Remove SingleThreadTaskRunner Support from SchedulerWorkerPoolImpl

base/task_scheduler/priority_queue_unittest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/task_scheduler/priority_queue.h"
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
@@ skipping 123 matching lines @@
 
   EXPECT_DCHECK_DEATH(
       {
         std::unique_ptr<PriorityQueue::Transaction> transaction_a =
             pq_a.BeginTransaction();
         std::unique_ptr<PriorityQueue::Transaction> transaction_b =
             pq_b.BeginTransaction();
       });
 }
 
-// Check that there is no crash when Transactions are created on the same thread
-// for 2 PriorityQueues which have a predecessor relationship.
-TEST(TaskSchedulerPriorityQueueTest, LegalTwoTransactionsSameThread) {
-  PriorityQueue pq_a;
-  PriorityQueue pq_b(&pq_a);
-
-  // This shouldn't crash.
-  std::unique_ptr<PriorityQueue::Transaction> transaction_a =
-      pq_a.BeginTransaction();
-  std::unique_ptr<PriorityQueue::Transaction> transaction_b =
-      pq_b.BeginTransaction();
-}
-
 // Check that it is possible to begin multiple Transactions for the same
 // PriorityQueue on different threads. The call to BeginTransaction() on the
 // second thread should block until the Transaction has ended on the first
 // thread.
 TEST(TaskSchedulerPriorityQueueTest, TwoTransactionsTwoThreads) {
   PriorityQueue pq;
 
   // Call BeginTransaction() on this thread and keep the Transaction alive.
   std::unique_ptr<PriorityQueue::Transaction> transaction =
       pq.BeginTransaction();
 
   // Call BeginTransaction() on another thread.
   ThreadBeginningTransaction thread_beginning_transaction(&pq);
   thread_beginning_transaction.Start();
 
   // After a few milliseconds, the call to BeginTransaction() on the other
   // thread should not have returned.
   thread_beginning_transaction.ExpectTransactionDoesNotBegin();
 
   // End the Transaction on the current thread.
   transaction.reset();
 
   // The other thread should exit after its call to BeginTransaction() returns.
   thread_beginning_transaction.Join();
 }
 
 }  // namespace internal
 }  // namespace base