[Reland] Optimize blink scheduler with an intrusive heap

third_party/WebKit/Source/platform/scheduler/base/time_domain.h

Index: third_party/WebKit/Source/platform/scheduler/base/time_domain.h
diff --git a/third_party/WebKit/Source/platform/scheduler/base/time_domain.h b/third_party/WebKit/Source/platform/scheduler/base/time_domain.h
index 52c7678eea23ac5de1257546e25a5172f24ea4fa..521caabaf79fda2d02084d47bd3df37de449b6f0 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/time_domain.h
+++ b/third_party/WebKit/Source/platform/scheduler/base/time_domain.h
@@ -13,6 +13,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
+#include "platform/scheduler/base/intrusive_heap.h"
 #include "platform/scheduler/base/lazy_now.h"
 #include "platform/scheduler/base/task_queue_impl.h"
 
@@ -134,20 +135,9 @@ class BLINK_PLATFORM_EXPORT TimeDomain {
  private:
   void MoveNewlyUpdatableQueuesIntoUpdatableQueueSet();
 
-  using DelayedWakeupMultimap =
-      std::multimap<base::TimeTicks, internal::TaskQueueImpl*>;
+  struct HeapElement;

[Sami, 2016/10/14 07:26:16]

Is there a more descriptive name for this? DelayedWakeup or something like that?

[alex clarke (OOO till 29th), 2016/10/14 13:55:36]

Done.

 
-  DelayedWakeupMultimap delayed_wakeup_multimap_;
-
-  // This map makes it easy to remove a queue from |delayed_wakeup_multimap_|.
-  // NOTE inserting or removing elements from a std::map does not invalidate any
-  // iterators.
-  using QueueToDelayedWakeupMultimapIteratorMap =
-      std::unordered_map<internal::TaskQueueImpl*,
-                         DelayedWakeupMultimap::iterator>;
-
-  QueueToDelayedWakeupMultimapIteratorMap
-      queue_to_delayed_wakeup_multimap_iterator_map_;
+  IntrusiveHeap<HeapElement> delayed_wakeup_queue_;
 
   // This lock guards only |newly_updatable_|.  It's not expected to be heavily
   // contended.