Redirect the MessageLoop's task runner to the renderer scheduler

components/scheduler/child/nestable_task_runner_for_test.h

 // 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.
 
 #ifndef CONTENT_RENDERER_SCHEDULER_NESTABLE_TASK_RUNNER_FOR_TEST_H_
 #define CONTENT_RENDERER_SCHEDULER_NESTABLE_TASK_RUNNER_FOR_TEST_H_
 
 #include "components/scheduler/child/nestable_single_thread_task_runner.h"
 
 namespace scheduler {
 
 class NestableTaskRunnerForTest : public NestableSingleThreadTaskRunner {
  public:
   static scoped_refptr<NestableTaskRunnerForTest> Create(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
   void SetNested(bool is_nested);
 
   // NestableSingleThreadTaskRunner implementation
+  void SetDefaultTaskRunner(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner) override;
   bool PostDelayedTask(const tracked_objects::Location& from_here,
                        const base::Closure& task,
                        base::TimeDelta delay) override;
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
                                   const base::Closure& task,
                                   base::TimeDelta delay) override;
   bool RunsTasksOnCurrentThread() const override;
   bool IsNested() const override;
   void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer) override;
   void RemoveTaskObserver(
       base::MessageLoop::TaskObserver* task_observer) override;
 
+  base::SingleThreadTaskRunner* default_task_runner() const {
+    return default_task_runner_.get();
+  }
+
  protected:
   ~NestableTaskRunnerForTest() override;
 
  private:
   NestableTaskRunnerForTest(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
   void WrapTask(const base::PendingTask* wrapped_task);
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> default_task_runner_;
   bool is_nested_;
 
   base::ObserverList<base::MessageLoop::TaskObserver> task_observers_;
 
   base::WeakPtr<NestableTaskRunnerForTest> weak_nestable_task_runner_ptr_;
   base::WeakPtrFactory<NestableTaskRunnerForTest> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NestableTaskRunnerForTest);
 };
 
 }  // namespace scheduler
 
 #endif  // CONTENT_RENDERER_SCHEDULER_NESTABLE_TASK_RUNNER_FOR_TEST_H_