Redirect the MessageLoop's task runner to the renderer scheduler

components/scheduler/child/scheduler_task_runner_delegate_impl_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/scheduler_task_runner_delegate_impl.h"
+
+#include "base/message_loop/message_loop.h"
+#include "base/test/test_simple_task_runner.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace scheduler {
+
+TEST(SchedulerTaskRunnerDelegateImplTest, TestTaskRunnerOverriding) {
+  base::MessageLoop loop;
+  scoped_refptr<base::SingleThreadTaskRunner> original_runner(
+      loop.task_runner());
+  scoped_refptr<base::SingleThreadTaskRunner> custom_runner(
+      new base::TestSimpleTaskRunner());
+  {
+    scoped_refptr<SchedulerTaskRunnerDelegateImpl> delegate(
+        SchedulerTaskRunnerDelegateImpl::Create(&loop));
+    delegate->SetDefaultTaskRunner(custom_runner);
+    DCHECK_EQ(custom_runner, loop.task_runner());
+  }
+  DCHECK_EQ(original_runner, loop.task_runner());
+}
+
+}  // namespace scheduler