Revert of [Reland] Optimize blink scheduler with an intrusive heap

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

 // Copyright 2015 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 THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_TIME_DOMAIN_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_TIME_DOMAIN_H_
 
 #include <map>
 
 #include "base/callback.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #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"
 
 namespace blink {
 namespace scheduler {
 namespace internal {
 class TaskQueueImpl;
 }  // internal
 class TaskQueueManager;
 class TaskQueueManagerDelegate;
@@ skipping 101 matching lines @@
   virtual void AsValueIntoInternal(
       base::trace_event::TracedValue* state) const = 0;
 
   // Call TaskQueueImpl::UpdateDelayedWorkQueue for each queue where the delay
   // has elapsed.
   void WakeupReadyDelayedQueues(LazyNow* lazy_now);
 
  private:
   void MoveNewlyUpdatableQueuesIntoUpdatableQueueSet();
 
-  struct DelayedWakeup {
-    base::TimeTicks time;
-    internal::TaskQueueImpl* queue;
+  using DelayedWakeupMultimap =
+      std::multimap<base::TimeTicks, internal::TaskQueueImpl*>;
 
-    bool operator<=(const DelayedWakeup& other) const {
-      if (time == other.time)
-        return queue < other.queue;
-      return time <= other.time;
-    }
+  DelayedWakeupMultimap delayed_wakeup_multimap_;
 
-    void SetHeapHandle(HeapHandle handle) { queue->set_heap_handle(handle); }
-  };
+  // 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>;
 
-  IntrusiveHeap<DelayedWakeup> delayed_wakeup_queue_;
+  QueueToDelayedWakeupMultimapIteratorMap
+      queue_to_delayed_wakeup_multimap_iterator_map_;
 
   // This lock guards only |newly_updatable_|.  It's not expected to be heavily
   // contended.
   base::Lock newly_updatable_lock_;
   std::vector<internal::TaskQueueImpl*> newly_updatable_;
 
   // Set of task queues with avaliable work on the incoming queue.  This should
   // only be accessed from the main thread.
   std::set<internal::TaskQueueImpl*> updatable_queue_set_;
 
   Observer* observer_;  // NOT OWNED.
 
   base::ThreadChecker main_thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(TimeDomain);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_TIME_DOMAIN_H_