[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..fcf236904d1165cfd37161b239b16e68a77f988f 100644
--- a/content/renderer/scheduler/renderer_scheduler_impl.h
+++ b/content/renderer/scheduler/renderer_scheduler_impl.h
@@ -111,6 +111,9 @@ 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;
+
   // IdleTaskDeadlineSupplier Implementation:
   void CurrentIdleTaskDeadlineCallback(base::TimeTicks* deadline_out) const;
 
@@ -127,6 +130,10 @@ 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();

[Sami, 2015/03/03 16:55:36]

Can this be const?

[rmcilroy, 2015/03/04 14:23:12]

Yes - done.

+
   // 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 +148,17 @@ 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,

[Sami, 2015/03/03 16:55:36]

nit: pass TimeTicks by value.

[rmcilroy, 2015/03/04 14:23:12]

Done.

+      base::TimeDelta* next_long_idle_period_delay_out);
+
+  // Initiate a long idle period.
+  void InitiateLongIdlePeriod();
+  void AfterWakeupInitiateLongIdlePeriod();

[Sami, 2015/03/03 16:55:36]

InitiateLongIdlePeriodAfterWakeup to make this less yoda?

[rmcilroy, 2015/03/04 14:23:12]

mmh, I originally had this but thought it sounded like it would initiate the
idle period after the next wakeup (not initiate the period now that we have
woken up).  But yeah, this is still probably better - done.

[rmcilroy, 2015/03/04 14:23:12]

Done.

+
   // Start and end an idle period.
   void StartIdlePeriod();
   void EndIdlePeriod();
@@ -159,6 +177,8 @@ 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_;
 
   // Don't access current_policy_ directly, instead use SchedulerPolicy().
   Policy current_policy_;