Implement PostDelayedTaskAt for guaranteed timer ordering

components/scheduler/child/idle_helper_unittest.cc

 // Copyright 2015 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 "components/scheduler/child/idle_helper.h"
 
 #include "base/callback.h"
 #include "base/test/simple_test_tick_clock.h"
 #include "cc/test/ordered_simple_task_runner.h"
 #include "components/scheduler/child/nestable_task_runner_for_test.h"
 #include "components/scheduler/child/scheduler_helper.h"
 #include "components/scheduler/child/scheduler_message_loop_delegate.h"
+#include "components/scheduler/child/task_queue.h"
 #include "components/scheduler/child/task_queue_manager.h"
 #include "components/scheduler/child/test_time_source.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using testing::_;
 using testing::AnyNumber;
 using testing::AtLeast;
 using testing::Exactly;
 using testing::Invoke;
@@ skipping 1115 matching lines @@
   EXPECT_EQ(0, run_count);
 
   default_task_runner_->PostDelayedTask(FROM_HERE, base::Bind(&NullTask),
                                         more_than_min_deadline_duration);
   idle_helper_->EnableLongIdlePeriod();
   RunUntilIdle();
   EXPECT_EQ(1, run_count);
 }
 
 }  // namespace scheduler