Redirect the MessageLoop's task runner to the renderer scheduler

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()
     : message_loop_(base::MessageLoop::current()),
       thread_id_(base::PlatformThread::CurrentId()) {
+  if (message_loop_)
+    original_task_runner_ = message_loop_->task_runner();
 }
 
 LazySchedulerMessageLoopDelegateForTests::
     ~LazySchedulerMessageLoopDelegateForTests() {
+  RestoreDefaultTaskRunner();
 }
 
 base::MessageLoop* LazySchedulerMessageLoopDelegateForTests::EnsureMessageLoop()
     const {
   if (message_loop_)
     return message_loop_;
   DCHECK(RunsTasksOnCurrentThread());
   message_loop_ = base::MessageLoop::current();
   DCHECK(message_loop_);
+  original_task_runner_ = message_loop_->task_runner();
   for (auto& observer : pending_observers_) {
     message_loop_->AddTaskObserver(observer);
   }
   pending_observers_.clear();
+  if (pending_task_runner_)
+    message_loop_->SetTaskRunner(pending_task_runner_.Pass());
   return message_loop_;
 }
 
+void LazySchedulerMessageLoopDelegateForTests::SetDefaultTaskRunner(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
+  if (!HasMessageLoop()) {
+    pending_task_runner_ = task_runner.Pass();
+    return;
+  }
+  message_loop_->SetTaskRunner(task_runner.Pass());
+}
+
+void LazySchedulerMessageLoopDelegateForTests::RestoreDefaultTaskRunner() {
+  if (HasMessageLoop() && base::MessageLoop::current() == message_loop_)
+    message_loop_->SetTaskRunner(original_task_runner_);
+}
+
 bool LazySchedulerMessageLoopDelegateForTests::HasMessageLoop() const {
   return message_loop_ != 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);
+  EnsureMessageLoop();
+  return original_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);
+  EnsureMessageLoop();
+  return original_task_runner_->PostNonNestableDelayedTask(from_here, task,
+                                                           delay);
 }
 
 bool LazySchedulerMessageLoopDelegateForTests::RunsTasksOnCurrentThread()
     const {
   return thread_id_ == base::PlatformThread::CurrentId();
 }
 
 bool LazySchedulerMessageLoopDelegateForTests::IsNested() const {
   return EnsureMessageLoop()->IsNested();
 }
@@ skipping 10 matching lines @@
 void LazySchedulerMessageLoopDelegateForTests::RemoveTaskObserver(
     base::MessageLoop::TaskObserver* task_observer) {
   if (!HasMessageLoop()) {
     pending_observers_.erase(task_observer);
     return;
   }
   EnsureMessageLoop()->RemoveTaskObserver(task_observer);
 }
 
 }  // namespace scheduler