Remove after wakeup logic and replace PumpTask with Fences

third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.h

Index: third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.h
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.h b/third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.h
index 0f3a99325e487b723096acaaaad7d7aa5838ed2a..ca9d4da695f197f1d98b920da02f89d59de3bbc3 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.h
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.h
@@ -19,6 +19,22 @@ class RendererSchedulerImpl;
 class ThrottledTimeDomain;
 class WebFrameSchedulerImpl;
 
+// The job of the ThrottlingHelper is to run tasks posted on throttled queues at
+// most once per second. This is done by disabling throttled queues and running
+// a special "heart beat" function |PumpThrottledTasks| which when run
+// temporarily enables throttled queues and posts a task on them to disable
+// themselves till next time.
+//
+// Of course the ThrottlingHelper isn't the only sub-system that wants to enable
+// or disable queues. E.g. RendererSchedulerImpl also does this for policy
+// reasons.  To prevent the systems from fighting, clients of ThrottlingHelper
+// must use SetQueueEnabled rather than calling the function directly on the
+// queue.
+//
+// There may be more than one system that wishes to throttle a queue (e.g.
+// renderer suspension vs level tab suspension) so the ThrottlingHelper keeps a

[Sami, 2016/08/25 15:54:13]

Did you mean renderer level vs. tab level suspension?

[alex clarke (OOO till 29th), 2016/08/26 13:29:09]

Done.

+// count of the number of systems that wish a queue to be throttled.
+// See IncreaseThrottleRefCount & DecreaseThrottleRefCount.
 class BLINK_PLATFORM_EXPORT ThrottlingHelper : public TimeDomain::Observer {
  public:
   ThrottlingHelper(RendererSchedulerImpl* renderer_scheduler,
@@ -50,6 +66,9 @@ class BLINK_PLATFORM_EXPORT ThrottlingHelper : public TimeDomain::Observer {
   // Removes |task_queue| from |throttled_queues_|.
   void UnregisterTaskQueue(TaskQueue* task_queue);
 
+  // Returns true if the |task_queue| is throttled.
+  bool IsThrottled(TaskQueue* task_queue) const;
+
   // Tells the ThrottlingHelper we're using virtual time, which disables all
   // throttling.
   void EnableVirtualTime();
@@ -73,6 +92,7 @@ class BLINK_PLATFORM_EXPORT ThrottlingHelper : public TimeDomain::Observer {
   using TaskQueueMap = std::map<TaskQueue*, Metadata>;
 
   void PumpThrottledTasks();
+  void MaybeDisableQueue(TaskQueue* task_queue);
 
   // Note |unthrottled_runtime| might be in the past. When this happens we
   // compute the delay to the next runtime based on now rather than
@@ -93,6 +113,7 @@ class BLINK_PLATFORM_EXPORT ThrottlingHelper : public TimeDomain::Observer {
   CancelableClosureHolder pump_throttled_tasks_closure_;
   base::TimeTicks pending_pump_throttled_tasks_runtime_;
   bool virtual_time_;
+  bool ignore_incoming_immediate_work_;
 
   base::WeakPtrFactory<ThrottlingHelper> weak_factory_;