Try a different way of unregistering TaskQueues from ThrottlingHelper

components/scheduler/renderer/web_frame_scheduler_impl.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/renderer/web_frame_scheduler_impl.h"
 
 #include "components/scheduler/base/real_time_domain.h"
 #include "components/scheduler/base/virtual_time_domain.h"
 #include "components/scheduler/child/web_task_runner_impl.h"
 #include "components/scheduler/renderer/renderer_scheduler_impl.h"
 #include "components/scheduler/renderer/web_view_scheduler_impl.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 
 namespace scheduler {
 
 WebFrameSchedulerImpl::WebFrameSchedulerImpl(
     RendererSchedulerImpl* renderer_scheduler,
     WebViewSchedulerImpl* parent_web_view_scheduler)
     : renderer_scheduler_(renderer_scheduler),
       parent_web_view_scheduler_(parent_web_view_scheduler),
       visible_(true),
       page_in_background_(false) {}
 
 WebFrameSchedulerImpl::~WebFrameSchedulerImpl() {
   if (loading_task_queue_.get())
     loading_task_queue_->UnregisterTaskQueue();
 
-  if (timer_task_queue_.get()) {
-    renderer_scheduler_->throttling_helper()->DecreaseThrottleRefCount(
-        timer_task_queue_.get());
+  if (timer_task_queue_.get())
     timer_task_queue_->UnregisterTaskQueue();
-  }
 
   if (parent_web_view_scheduler_)
     parent_web_view_scheduler_->Unregister(this);
 }
 
 void WebFrameSchedulerImpl::DetachFromWebViewScheduler() {
   parent_web_view_scheduler_ = nullptr;
 }
 
 void WebFrameSchedulerImpl::setFrameVisible(bool visible) {
@@ skipping 41 matching lines @@
   if (page_in_background_) {
     renderer_scheduler_->throttling_helper()->IncreaseThrottleRefCount(
         timer_task_queue_.get());
   } else {
     renderer_scheduler_->throttling_helper()->DecreaseThrottleRefCount(
         timer_task_queue_.get());
   }
 }
 
 }  // namespace scheduler