TaskScheduler: Add FlushForTesting().

base/task_scheduler/task_scheduler_impl.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/task_scheduler_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 39 matching lines @@
     ExecutionMode execution_mode) {
   return GetWorkerPoolForTraits(traits)->CreateTaskRunnerWithTraits(
       traits, execution_mode);
 }
 
 void TaskSchedulerImpl::Shutdown() {
   // TODO(fdoray): Increase the priority of BACKGROUND tasks blocking shutdown.
   task_tracker_.Shutdown();
 }
 
+void TaskSchedulerImpl::FlushForTesting() {
+  task_tracker_.Flush();
+}
+
 void TaskSchedulerImpl::JoinForTesting() {
 #if DCHECK_IS_ON()
   DCHECK(!join_for_testing_returned_.IsSet());
 #endif
   for (const auto& worker_pool : worker_pools_)
     worker_pool->JoinForTesting();
   service_thread_->JoinForTesting();
 #if DCHECK_IS_ON()
   join_for_testing_returned_.Set();
 #endif
@@ skipping 54 matching lines @@
   GetWorkerPoolForTraits(traits)->ReEnqueueSequence(std::move(sequence),
                                                     sort_key);
 }
 
 void TaskSchedulerImpl::OnDelayedRunTimeUpdated() {
   service_thread_->WakeUp();
 }
 
 }  // namespace internal
 }  // namespace base