scheduler: Turn expensive task blocking into a finch trial

components/scheduler/renderer/renderer_scheduler_impl.h

 // 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.
 
 #ifndef COMPONENTS_SCHEDULER_RENDERER_RENDERER_SCHEDULER_IMPL_H_
 #define COMPONENTS_SCHEDULER_RENDERER_RENDERER_SCHEDULER_IMPL_H_
 
 #include "base/atomicops.h"
 #include "base/macros.h"
 #include "base/synchronization/lock.h"
@@ skipping 73 matching lines @@
 
   // 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();
 
   void RegisterTimeDomain(TimeDomain* time_domain);
   void UnregisterTimeDomain(TimeDomain* time_domain);
 
+  void SetExpensiveTaskBlockingAllowed(bool allowed);
+
   // Test helpers.
   SchedulerHelper* GetSchedulerHelperForTesting();
   TaskCostEstimator* GetLoadingTaskCostEstimatorForTesting();
   TaskCostEstimator* GetTimerTaskCostEstimatorForTesting();
   IdleTimeEstimator* GetIdleTimeEstimatorForTesting();
   base::TimeTicks CurrentIdleTaskDeadlineForTesting() const;
 
   base::TickClock* tick_clock() const;
 
   RealTimeDomain* real_time_domain() const {
@@ skipping 184 matching lines @@
     bool renderer_backgrounded;
     bool timer_queue_suspension_when_backgrounded_enabled;
     bool timer_queue_suspended_when_backgrounded;
     bool was_shutdown;
     bool loading_tasks_seem_expensive;
     bool timer_tasks_seem_expensive;
     bool touchstart_expected_soon;
     bool have_seen_a_begin_main_frame;
     bool has_visible_render_widget_with_touch_handler;
     bool begin_frame_not_expected_soon;
+    bool expensive_task_blocking_allowed;
   };
 
   struct AnyThread {
     AnyThread();
     ~AnyThread();
 
     base::TimeTicks last_idle_period_end_time;
     base::TimeTicks rails_loading_priority_deadline;
     base::TimeTicks fling_compositor_escalation_deadline;
     UserModel user_model;
@@ skipping 54 matching lines @@
 
   PollableThreadSafeFlag policy_may_need_update_;
   base::WeakPtrFactory<RendererSchedulerImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererSchedulerImpl);
 };
 
 }  // namespace scheduler
 
 #endif  // COMPONENTS_SCHEDULER_RENDERER_RENDERER_SCHEDULER_IMPL_H_