Added zone tracing

src/zone/accounting-allocator.h

 // Copyright 2016 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_ZONE_ACCOUNTING_ALLOCATOR_H_
 #define V8_ZONE_ACCOUNTING_ALLOCATOR_H_
 
 #include "include/v8-platform.h"
 #include "src/base/atomic-utils.h"
 #include "src/base/atomicops.h"
@@ skipping 17 matching lines @@
   // them if the pool is already full or memory pressure is high.
   virtual void ReturnSegment(Segment* memory);
 
   size_t GetCurrentMemoryUsage() const;
   size_t GetMaxMemoryUsage() const;
 
   size_t GetCurrentPoolSize() const;
 
   void MemoryPressureNotification(MemoryPressureLevel level);
 
+  virtual void ZoneCreation(const Zone* zone) {}
+  virtual void ZoneDestruction(const Zone* zone) {}
+
  private:
   static const uint8_t kMinSegmentSizePower = 13;
   static const uint8_t kMaxSegmentSizePower = 18;
   static const uint8_t kMaxSegmentsPerBucket = 5;
 
   STATIC_ASSERT(kMinSegmentSizePower <= kMaxSegmentSizePower);
 
   // Allocates a new segment. Returns nullptr on failed allocation.
   Segment* AllocateSegment(size_t bytes);
   void FreeSegment(Segment* memory);
@@ skipping 19 matching lines @@
 
   base::AtomicValue<MemoryPressureLevel> memory_pressure_level_;
 
   DISALLOW_COPY_AND_ASSIGN(AccountingAllocator);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ZONE_ACCOUNTING_ALLOCATOR_H_