Try a different way of unregistering TaskQueues from ThrottlingHelper

components/scheduler/renderer/renderer_scheduler_impl.cc

Index: components/scheduler/renderer/renderer_scheduler_impl.cc
diff --git a/components/scheduler/renderer/renderer_scheduler_impl.cc b/components/scheduler/renderer/renderer_scheduler_impl.cc
index 1c08a14ce2afa7aabe2a7e36127f41ccf67e3dad..a752bb7464dc424d8a4d72236eaaa9a780f19a03 100644
--- a/components/scheduler/renderer/renderer_scheduler_impl.cc
+++ b/components/scheduler/renderer/renderer_scheduler_impl.cc
@@ -224,6 +224,9 @@ RendererSchedulerImpl::NewRenderWidgetSchedulingState() {
 
 void RendererSchedulerImpl::OnUnregisterTaskQueue(
     const scoped_refptr<TaskQueue>& task_queue) {
+  if (throttling_helper_.get())
+    throttling_helper_->UnregisterTaskQueue(task_queue.get());
+
   if (loading_task_runners_.find(task_queue) != loading_task_runners_.end()) {
     task_queue->RemoveTaskObserver(
         &MainThreadOnly().loading_task_cost_estimator);