TaskScheduler [11] Support ExecutionMode::SINGLE_THREADED.

base/task_scheduler/scheduler_thread_pool.cc

Index: base/task_scheduler/scheduler_thread_pool.cc
diff --git a/base/task_scheduler/scheduler_thread_pool.cc b/base/task_scheduler/scheduler_thread_pool.cc
index 1ac547f5cb6cf13243fde345bef1d8cb6fa693bc..8a8d3819b308181c17abd744e4ab92ea9c3debcf 100644
--- a/base/task_scheduler/scheduler_thread_pool.cc
+++ b/base/task_scheduler/scheduler_thread_pool.cc
@@ -125,8 +125,9 @@ class SchedulerThreadPool::SchedulerWorkerThreadDelegateImpl
 
   // SchedulerWorkerThread::Delegate:
   void OnMainEntry() override;
-  scoped_refptr<Sequence> GetWork(
-      SchedulerWorkerThread* worker_thread) override;
+  scoped_refptr<Sequence> GetWork(SchedulerWorkerThread* worker_thread,
+                                  PriorityQueue* single_threaded_priority_queue,
+                                  bool* is_single_threaded_sequence) override;
   void EnqueueSequence(scoped_refptr<Sequence> sequence) override;
 
  private:
@@ -241,7 +242,12 @@ void SchedulerThreadPool::SchedulerWorkerThreadDelegateImpl::OnMainEntry() {
 
 scoped_refptr<Sequence>
 SchedulerThreadPool::SchedulerWorkerThreadDelegateImpl::GetWork(
-    SchedulerWorkerThread* worker_thread) {
+    SchedulerWorkerThread* worker_thread,
+    PriorityQueue* single_threaded_priority_queue,
+    bool* is_single_threaded_sequence) {
+  // TODO(fdoray): Return a Sequence from |single_threaded_priority_queue| when
+  // appropriate.
+
   std::unique_ptr<PriorityQueue::Transaction> transaction(
       outer_->shared_priority_queue_.BeginTransaction());
   const auto sequence_and_sort_key = transaction->Peek();
@@ -298,7 +304,8 @@ bool SchedulerThreadPool::Initialize(ThreadPriority thread_priority,
   for (size_t i = 0; i < max_threads; ++i) {
     std::unique_ptr<SchedulerWorkerThread> worker_thread =
         SchedulerWorkerThread::CreateSchedulerWorkerThread(
-            thread_priority, worker_thread_delegate_.get(), task_tracker_);
+            thread_priority, worker_thread_delegate_.get(), task_tracker_,
+            delayed_task_manager_, &shared_priority_queue_);
     if (!worker_thread)
       break;
     idle_worker_threads_stack_.push(worker_thread.get());