Correctly handle the case when TimerTask is destroyed with being run.

src/heap/memory-reducer.h

 // Copyright 2015 the V8 project 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 V8_HEAP_memory_reducer_H
 #define V8_HEAP_memory_reducer_H
 
 #include "include/v8-platform.h"
 #include "src/base/macros.h"
 
@@ skipping 96 matching lines @@
   void NotifyTimer(const Event& event);
   void NotifyMarkCompact(const Event& event);
   void NotifyContextDisposed(const Event& event);
   void NotifyBackgroundIdleNotification(const Event& event);
   // The step function that computes the next state from the current state and
   // the incoming event.
   static State Step(const State& state, const Event& event);
   // Posts a timer task that will call NotifyTimer after the given delay.
   void ScheduleTimer(double delay_ms);
   void TearDown();
-
+  void ClearTask(v8::Task* task);
   static const int kLongDelayMs;
   static const int kShortDelayMs;
   static const int kMaxNumberOfGCs;
 
   Heap* heap() { return heap_; }
 
  private:
   class TimerTask : public v8::Task {
    public:
     explicit TimerTask(MemoryReducer* memory_reducer)
         : memory_reducer_(memory_reducer), heap_is_torn_down_(false) {}
-    virtual ~TimerTask() {}
+    virtual ~TimerTask() {
+      if (!heap_is_torn_down_) {
+        memory_reducer_->ClearTask(this);
+      }
+    }
     void NotifyHeapTearDown() { heap_is_torn_down_ = true; }
 
    private:
     // v8::Task overrides.
     void Run() override;
     MemoryReducer* memory_reducer_;
     bool heap_is_torn_down_;
     DISALLOW_COPY_AND_ASSIGN(TimerTask);
   };
   Heap* heap_;
   State state_;
   TimerTask* pending_task_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryReducer);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_memory_reducer_H