Throttling Helper to disable task queue until PumpThrottledTasks called

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/logging.h"
 #include "base/memory/ptr_util.h"
@@ skipping 826 matching lines @@
                        new_policy.default_queue_policy);
 
   DCHECK(compositor_task_runner_->IsQueueEnabled());
   MainThreadOnly().current_policy = new_policy;
 }
 
 void RendererSchedulerImpl::ApplyTaskQueuePolicy(
     TaskQueue* task_queue,
     const TaskQueuePolicy& old_task_queue_policy,
     const TaskQueuePolicy& new_task_queue_policy) const {
-  task_queue->SetQueueEnabled(new_task_queue_policy.is_enabled);
+  // The ThrottlingHelper also calls SetQueueEnabled, so we can avoid calling
+  // this here.
+  if (new_task_queue_policy.time_domain_type != TimeDomainType::THROTTLED)
+    task_queue->SetQueueEnabled(new_task_queue_policy.is_enabled);
   if (old_task_queue_policy.priority != new_task_queue_policy.priority)
     task_queue->SetQueuePriority(new_task_queue_policy.priority);
 
   if (old_task_queue_policy.time_domain_type !=
       new_task_queue_policy.time_domain_type) {
     if (new_task_queue_policy.time_domain_type == TimeDomainType::THROTTLED) {
       throttling_helper_->IncreaseThrottleRefCount(task_queue);
     } else if (old_task_queue_policy.time_domain_type ==
                TimeDomainType::THROTTLED) {
       throttling_helper_->DecreaseThrottleRefCount(task_queue);
@@ skipping 402 matching lines @@
     }
     MainThreadOnly().have_reported_blocking_intervention_since_navigation =
         true;
     BroadcastConsoleWarning(
         "Deferred long-running timer task(s) to improve scrolling smoothness. "
         "See crbug.com/574343.");
   }
 }
 
 }  // namespace scheduler