[content]: Add support for long idle times in the Blink Scheduler.

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 93 matching lines @@
   static const char* InputStreamStateToString(InputStreamState state);
 
   static InputStreamState ComputeNewInputStreamState(
       InputStreamState current_state,
       blink::WebInputEvent::Type new_input_event,
       blink::WebInputEvent::Type last_input_event);
 
   // The time we should stay in a priority-escalated mode after an input event.
   static const int kPriorityEscalationAfterInputMillis = 100;
 
+  // The maximum length of an idle period.
+  static const int kMaximumIdlePeriodMillis = 50;
+
+  // The minimum delay to wait between retrying to initiate a long idle time.
+  static const int kRetryInitiateLongIdlePeriodDelayMillis = 1;
+
   // 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);
 
   // 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();
 
+  // Returns the amount of time left in the current input escalated priority
+  // policy.
+  base::TimeDelta TimeLeftInInputEscalatedPolicy() const;
+
   // 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);
 
   // Called when a previously queued input event was processed.
   // |begin_frame_time|, if non-zero, identifies the frame time at which the
   // input was processed.
   void DidProcessInputEvent(base::TimeTicks begin_frame_time);
 
+  // Returns true if we should initiate a long idle time now. Fills in
+  // |next_long_idle_period_delay_out| with the next time we should try to
+  // initiate the next idle period.
+  bool ShouldStartLongIdlePeriod(
+      const base::TimeTicks now,
+      base::TimeDelta* next_long_idle_period_delay_out);
+
+  // Initiate a long idle period.
+  void InitiateLongIdlePeriod();
+  void InitiateLongIdlePeriodAfterWakeup();
+
   // Start and end an idle period.
   void StartIdlePeriod();
   void EndIdlePeriod();
 
   base::TimeTicks Now() const;
 
   base::ThreadChecker main_thread_checker_;
   scoped_ptr<RendererTaskQueueSelector> renderer_task_queue_selector_;
   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 initiate_next_long_idle_period_closure_;
+  CancelableClosureHolder after_wakeup_initiate_next_long_idle_period_closure_;

[Sami, 2015/03/04 18:26:40]

nit: swap the names around to match the function name.

 
   // Don't access current_policy_ directly, instead use SchedulerPolicy().
   Policy current_policy_;
+  bool in_idle_period_;

[Sami, 2015/03/04 18:26:40]

Looks like this isn't initialized in the constructor. Mind dumping this to the
state trace too?

[rmcilroy, 2015/03/05 11:48:52]

Done and done.

 
   base::TimeTicks estimated_next_frame_begin_;
+  base::TimeTicks current_policy_expiration_time_;
 
   // 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_