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

content/renderer/scheduler/renderer_scheduler_impl.h

Index: content/renderer/scheduler/renderer_scheduler_impl.h
diff --git a/content/renderer/scheduler/renderer_scheduler_impl.h b/content/renderer/scheduler/renderer_scheduler_impl.h
index c908a974a0d8f21cf24f8cb34d36fc053a1d68c8..3b21599e38a4c13b30d73c27a26061f89991458d 100644
--- a/content/renderer/scheduler/renderer_scheduler_impl.h
+++ b/content/renderer/scheduler/renderer_scheduler_impl.h
@@ -111,6 +111,12 @@ class CONTENT_EXPORT RendererSchedulerImpl : public RendererScheduler {
   // 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;
 
@@ -127,6 +133,10 @@ class CONTENT_EXPORT RendererSchedulerImpl : public RendererScheduler {
   // 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
@@ -141,6 +151,17 @@ class CONTENT_EXPORT RendererSchedulerImpl : public RendererScheduler {
   // 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();
@@ -159,11 +180,15 @@ class CONTENT_EXPORT RendererSchedulerImpl : public RendererScheduler {
 
   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.