Redirect the MessageLoop's task runner to the renderer scheduler

components/scheduler/child/scheduler_message_loop_delegate.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/scheduler_message_loop_delegate.h"
 
 namespace scheduler {
 
 // static
 scoped_refptr<SchedulerMessageLoopDelegate>
 SchedulerMessageLoopDelegate::Create(base::MessageLoop* message_loop) {
   return make_scoped_refptr(new SchedulerMessageLoopDelegate(message_loop));
 }
 
 SchedulerMessageLoopDelegate::SchedulerMessageLoopDelegate(
     base::MessageLoop* message_loop)
-    : message_loop_(message_loop) {
+    : message_loop_(message_loop),
+      message_loop_task_runner_(message_loop->task_runner()) {
 }
 
 SchedulerMessageLoopDelegate::~SchedulerMessageLoopDelegate() {
+  // Restore the original task runner to the message loop.
+  message_loop_->SetTaskRunner(message_loop_task_runner_);
+}
+
+void SchedulerMessageLoopDelegate::SetDefaultTaskRunner(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
+  message_loop_->SetTaskRunner(task_runner);
 }
 
 bool SchedulerMessageLoopDelegate::PostDelayedTask(
     const tracked_objects::Location& from_here,
     const base::Closure& task,
     base::TimeDelta delay) {
-  return message_loop_->task_runner()->PostDelayedTask(from_here, task, delay);
+  return message_loop_task_runner_->PostDelayedTask(from_here, task, delay);
 }
 
 bool SchedulerMessageLoopDelegate::PostNonNestableDelayedTask(
     const tracked_objects::Location& from_here,
     const base::Closure& task,
     base::TimeDelta delay) {
-  return message_loop_->task_runner()->PostNonNestableDelayedTask(from_here,
-                                                                  task, delay);
+  return message_loop_task_runner_->PostNonNestableDelayedTask(from_here, task,
+                                                               delay);
 }
 
 bool SchedulerMessageLoopDelegate::RunsTasksOnCurrentThread() const {
-  return message_loop_->task_runner()->RunsTasksOnCurrentThread();
+  return message_loop_task_runner_->RunsTasksOnCurrentThread();
 }
 
 bool SchedulerMessageLoopDelegate::IsNested() const {
   return message_loop_->IsNested();
 }
 
 void SchedulerMessageLoopDelegate::AddTaskObserver(
     base::MessageLoop::TaskObserver* task_observer) {
   return message_loop_->AddTaskObserver(task_observer);
 }
 
 void SchedulerMessageLoopDelegate::RemoveTaskObserver(
     base::MessageLoop::TaskObserver* task_observer) {
   return message_loop_->RemoveTaskObserver(task_observer);
 }
 
 }  // namespace scheduler