Revert of scheduler: Always create a real scheduler in unit tests

components/scheduler/test/lazy_scheduler_message_loop_delegate_for_tests.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/test/lazy_scheduler_message_loop_delegate_for_tests.h"
-
-namespace scheduler {
-
-// static
-scoped_refptr<LazySchedulerMessageLoopDelegateForTests>
-LazySchedulerMessageLoopDelegateForTests::Create() {
-  return make_scoped_refptr(new LazySchedulerMessageLoopDelegateForTests());
-}
-
-LazySchedulerMessageLoopDelegateForTests::
-    LazySchedulerMessageLoopDelegateForTests()
-    : thread_id_(base::PlatformThread::CurrentId()) {
-}
-
-LazySchedulerMessageLoopDelegateForTests::
-    ~LazySchedulerMessageLoopDelegateForTests() {
-}
-
-base::MessageLoop* LazySchedulerMessageLoopDelegateForTests::EnsureMessageLoop()
-    const {
-  base::MessageLoop* message_loop = base::MessageLoop::current();
-  DCHECK(message_loop);
-  for (auto& observer : pending_observers_) {
-    message_loop->AddTaskObserver(observer);
-  }
-  pending_observers_.clear();
-  return message_loop;
-}
-
-bool LazySchedulerMessageLoopDelegateForTests::HasMessageLoop() const {
-  return base::MessageLoop::current() != nullptr;
-}
-
-bool LazySchedulerMessageLoopDelegateForTests::PostDelayedTask(
-    const tracked_objects::Location& from_here,
-    const base::Closure& task,
-    base::TimeDelta delay) {
-  return EnsureMessageLoop()->task_runner()->PostDelayedTask(from_here, task,
-                                                             delay);
-}
-
-bool LazySchedulerMessageLoopDelegateForTests::PostNonNestableDelayedTask(
-    const tracked_objects::Location& from_here,
-    const base::Closure& task,
-    base::TimeDelta delay) {
-  return EnsureMessageLoop()->task_runner()->PostNonNestableDelayedTask(
-      from_here, task, delay);
-}
-
-bool LazySchedulerMessageLoopDelegateForTests::RunsTasksOnCurrentThread()
-    const {
-  return thread_id_ == base::PlatformThread::CurrentId();
-}
-
-bool LazySchedulerMessageLoopDelegateForTests::IsNested() const {
-  return EnsureMessageLoop()->IsNested();
-}
-
-void LazySchedulerMessageLoopDelegateForTests::AddTaskObserver(
-    base::MessageLoop::TaskObserver* task_observer) {
-  if (!HasMessageLoop()) {
-    pending_observers_.insert(task_observer);
-    return;
-  }
-  EnsureMessageLoop()->AddTaskObserver(task_observer);
-}
-
-void LazySchedulerMessageLoopDelegateForTests::RemoveTaskObserver(
-    base::MessageLoop::TaskObserver* task_observer) {
-  if (!HasMessageLoop()) {
-    pending_observers_.erase(task_observer);
-    return;
-  }
-  EnsureMessageLoop()->RemoveTaskObserver(task_observer);
-}
-
-}  // namespace scheduler