Prevent multiple pending UpdatePolicy tasks.

content/renderer/scheduler/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 CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_IMPL_H_
 #define CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_IMPL_H_
 
 #include "base/atomicops.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
@@ skipping 35 matching lines @@
   void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer) override;
   void RemoveTaskObserver(
       base::MessageLoop::TaskObserver* task_observer) override;
   void Shutdown() override;
 
   void SetTimeSourceForTesting(scoped_refptr<cc::TestNowSource> time_source);
   void SetWorkBatchSizeForTesting(size_t work_batch_size);
 
  private:
   friend class RendererSchedulerImplTest;
+  friend class MockRendererSchedulerImpl;
 
   // Keep RendererSchedulerImpl::TaskQueueIdToString in sync with this enum.
   enum QueueId {
     DEFAULT_TASK_QUEUE,
     COMPOSITOR_TASK_QUEUE,
     LOADING_TASK_QUEUE,
     IDLE_TASK_QUEUE,
     CONTROL_TASK_QUEUE,
     CONTROL_TASK_AFTER_WAKEUP_QUEUE,
     // Must be the last entry.
@@ skipping 45 matching lines @@
   // The time we should stay in a priority-escalated mode after an input event.
   static const int kPriorityEscalationAfterInputMillis = 100;
 
   // IdleTaskDeadlineSupplier Implementation:
   void CurrentIdleTaskDeadlineCallback(base::TimeTicks* deadline_out) const;
 
   // Returns the current scheduler policy. Must be called from the main thread.
   Policy SchedulerPolicy() const;
 
   // Posts a call to UpdatePolicy on the control runner to be run after |delay|
-  void PostUpdatePolicyOnControlRunner(base::TimeDelta delay);
+  // Ensures that there can only be one pending delayed and one non-delayed
+  // UpdatePolicy task.
+  void PostUpdatePolicyOnControlRunnerLocked(base::TimeDelta delay);

[Sami, 2015/03/10 16:19:38]

Should we call this MaybePost... to match the other functions that do similar
things?

 
   // Update the policy if a new signal has arrived. Must be called from the main
   // thread.
   void MaybeUpdatePolicy();
 
-  // Updates the scheduler policy. Must be called from the main thread.
-  void UpdatePolicy();
+  // Updates the scheduler policy. Must be called from the main thread. If
+  // |clear_pending_non_delayed_update_policy| is true then
+  // pending_non_delayed_update_policy_ will be set to false.
+  virtual void UpdatePolicy(bool clear_pending_non_delayed_update_policy);
 
   // Helper for computing the new policy. |new_policy_duration| will be filled
   // with the amount of time after which the policy should be updated again. If
   // the duration is zero, a new policy update will not be scheduled. Must be
   // called with |incoming_signals_lock_| held.
   Policy ComputeNewPolicy(base::TimeDelta* new_policy_duration);
 
   // An input event of some sort happened, the policy may need updating.
   void UpdateForInputEvent(blink::WebInputEvent::Type type);
 
@@ skipping 13 matching lines @@
   scoped_ptr<TaskQueueManager> task_queue_manager_;
   scoped_refptr<base::SingleThreadTaskRunner> control_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> control_task_after_wakeup_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> default_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> compositor_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> loading_task_runner_;
   scoped_refptr<SingleThreadIdleTaskRunner> idle_task_runner_;
 
   base::Closure update_policy_closure_;
   CancelableClosureHolder end_idle_period_closure_;
+  CancelableClosureHolder delayed_update_policy_closure_;
+  bool pending_non_delayed_update_policy_;
 
   // Don't access current_policy_ directly, instead use SchedulerPolicy().
   Policy current_policy_;
 
   base::TimeTicks estimated_next_frame_begin_;
 
   // The incoming_signals_lock_ mutex protects access to all variables in the
   // (contiguous) block below.
   base::Lock incoming_signals_lock_;
   base::TimeTicks last_input_receipt_time_on_compositor_;
   base::TimeTicks last_input_process_time_on_main_;
   blink::WebInputEvent::Type last_input_type_;
   InputStreamState input_stream_state_;
   PollableNeedsUpdateFlag policy_may_need_update_;
 
   scoped_refptr<cc::TestNowSource> time_source_;
 
   base::WeakPtr<RendererSchedulerImpl> weak_renderer_scheduler_ptr_;
   base::WeakPtrFactory<RendererSchedulerImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererSchedulerImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_IMPL_H_