Separate the create and start phases in 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/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 69 matching lines @@
   scoped_refptr<Sequence> sequence_d(new Sequence);
   sequence_d->PushTask(MakeUnique<Task>(
       FROM_HERE, Bind(&DoNothing),
       TaskTraits().WithPriority(TaskPriority::BACKGROUND), TimeDelta()));
   SequenceSortKey sort_key_d = sequence_d->GetSortKey();
 
   // Create a PriorityQueue and a Transaction.
   PriorityQueue pq;
   auto transaction(pq.BeginTransaction());
   EXPECT_TRUE(transaction->IsEmpty());
+  EXPECT_EQ(0U, transaction->Size());
 
   // Push |sequence_a| in the PriorityQueue. It becomes the sequence with the
   // highest priority.
   transaction->Push(sequence_a, sort_key_a);
   EXPECT_EQ(sort_key_a, transaction->PeekSortKey());
+  EXPECT_EQ(1U, transaction->Size());
 
   // Push |sequence_b| in the PriorityQueue. It becomes the sequence with the
   // highest priority.
   transaction->Push(sequence_b, sort_key_b);
   EXPECT_EQ(sort_key_b, transaction->PeekSortKey());
+  EXPECT_EQ(2U, transaction->Size());
 
   // Push |sequence_c| in the PriorityQueue. |sequence_b| is still the sequence
   // with the highest priority.
   transaction->Push(sequence_c, sort_key_c);
   EXPECT_EQ(sort_key_b, transaction->PeekSortKey());
+  EXPECT_EQ(3U, transaction->Size());
 
   // Push |sequence_d| in the PriorityQueue. |sequence_b| is still the sequence
   // with the highest priority.
   transaction->Push(sequence_d, sort_key_d);
   EXPECT_EQ(sort_key_b, transaction->PeekSortKey());
+  EXPECT_EQ(4U, transaction->Size());
 
   // Pop |sequence_b| from the PriorityQueue. |sequence_c| becomes the sequence
   // with the highest priority.
   EXPECT_EQ(sequence_b, transaction->PopSequence());
   EXPECT_EQ(sort_key_c, transaction->PeekSortKey());
+  EXPECT_EQ(3U, transaction->Size());
 
   // Pop |sequence_c| from the PriorityQueue. |sequence_a| becomes the sequence
   // with the highest priority.
   EXPECT_EQ(sequence_c, transaction->PopSequence());
   EXPECT_EQ(sort_key_a, transaction->PeekSortKey());
+  EXPECT_EQ(2U, transaction->Size());
 
   // Pop |sequence_a| from the PriorityQueue. |sequence_d| becomes the sequence
   // with the highest priority.
   EXPECT_EQ(sequence_a, transaction->PopSequence());
   EXPECT_EQ(sort_key_d, transaction->PeekSortKey());
+  EXPECT_EQ(1U, transaction->Size());
 
   // Pop |sequence_d| from the PriorityQueue. It is now empty.
   EXPECT_EQ(sequence_d, transaction->PopSequence());
   EXPECT_TRUE(transaction->IsEmpty());
+  EXPECT_EQ(0U, transaction->Size());
 }
 
 // Check that creating Transactions on the same thread for 2 unrelated
 // PriorityQueues causes a crash.
 TEST(TaskSchedulerPriorityQueueTest, IllegalTwoTransactionsSameThread) {
   PriorityQueue pq_a;
   PriorityQueue pq_b;
 
   EXPECT_DCHECK_DEATH(
       {
@@ skipping 25 matching lines @@
 
   // 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