Move throttling of background timers into the renderer scheduler

components/scheduler/renderer/renderer_scheduler_impl.h

Index: components/scheduler/renderer/renderer_scheduler_impl.h
diff --git a/components/scheduler/renderer/renderer_scheduler_impl.h b/components/scheduler/renderer/renderer_scheduler_impl.h
index 6fb097a19a77ede866d0145e0fc64b9b43b0d558..a44dcdcfe28536edb0f0a7803388c373068ce484 100644
--- a/components/scheduler/renderer/renderer_scheduler_impl.h
+++ b/components/scheduler/renderer/renderer_scheduler_impl.h
@@ -82,6 +82,9 @@ class SCHEDULER_EXPORT RendererSchedulerImpl
   // TaskQueueManager::Observer implementation:
   void OnUnregisterTaskQueue(const scoped_refptr<TaskQueue>& queue) override;
 
+  // Returns a task runner where tasks run at the highest possible priority.
+  scoped_refptr<TaskQueue> ControlTaskRunner();
+
   // Test helpers.
   SchedulerHelper* GetSchedulerHelperForTesting();
   TaskCostEstimator* GetLoadingTaskCostEstimatorForTesting();