Revert of Redirect the MessageLoop's task runner to the renderer scheduler

components/scheduler/renderer/renderer_scheduler_impl.cc

 // Copyright 2014 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/renderer/renderer_scheduler_impl.h"
 
 #include "base/bind.h"
 #include "base/debug/stack_trace.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/output/begin_frame_args.h"
+#include "components/scheduler/child/nestable_single_thread_task_runner.h"
 #include "components/scheduler/child/prioritizing_task_queue_selector.h"
-#include "components/scheduler/child/scheduler_task_runner_delegate.h"
 
 namespace scheduler {
 
 RendererSchedulerImpl::RendererSchedulerImpl(
-    scoped_refptr<SchedulerTaskRunnerDelegate> main_task_runner)
+    scoped_refptr<NestableSingleThreadTaskRunner> main_task_runner)
     : helper_(main_task_runner,
               "renderer.scheduler",
               TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
               TRACE_DISABLED_BY_DEFAULT("renderer.scheduler.debug"),
               TASK_QUEUE_COUNT),
       idle_helper_(&helper_,
                    this,
                    IDLE_TASK_QUEUE,
                    "renderer.scheduler",
                    TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
@@ skipping 670 matching lines @@
   UpdatePolicyLocked(UpdateType::MAY_EARLY_OUT_IF_POLICY_UNCHANGED);
 }
 
 bool RendererSchedulerImpl::HadAnIdlePeriodRecently(base::TimeTicks now) const {
   return (now - AnyThread().last_idle_period_end_time_) <=
          base::TimeDelta::FromMilliseconds(
              kIdlePeriodStarvationThresholdMillis);
 }
 
 }  // namespace scheduler