Replaced different means of zone pooling/reusing by one zone segment pool

src/compiler/zone-stats.h

 // Copyright 2014 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_COMPILER_ZONE_POOL_H_
-#define V8_COMPILER_ZONE_POOL_H_
+#ifndef V8_COMPILER_ZONE_STATS_H_
+#define V8_COMPILER_ZONE_STATS_H_
 
 #include <map>
 #include <set>
 #include <vector>
 
 #include "src/zone/zone.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-class ZonePool final {
+class ZoneStats final {
  public:
   class Scope final {
    public:
-    explicit Scope(ZonePool* zone_pool)
-        : zone_pool_(zone_pool), zone_(nullptr) {}
+    explicit Scope(ZoneStats* zone_stats)
+        : zone_stats_(zone_stats), zone_(nullptr) {}
     ~Scope() { Destroy(); }
 
     Zone* zone() {
-      if (zone_ == nullptr) zone_ = zone_pool_->NewEmptyZone();
+      if (zone_ == nullptr) zone_ = zone_stats_->NewEmptyZone();
       return zone_;
     }
     void Destroy() {
-      if (zone_ != nullptr) zone_pool_->ReturnZone(zone_);
+      if (zone_ != nullptr) zone_stats_->ReturnZone(zone_);
       zone_ = nullptr;
     }
 
    private:
-    ZonePool* const zone_pool_;
+    ZoneStats* const zone_stats_;
     Zone* zone_;
     DISALLOW_COPY_AND_ASSIGN(Scope);
   };
 
   class StatsScope final {
    public:
-    explicit StatsScope(ZonePool* zone_pool);
+    explicit StatsScope(ZoneStats* zone_stats);
     ~StatsScope();
 
     size_t GetMaxAllocatedBytes();
     size_t GetCurrentAllocatedBytes();
     size_t GetTotalAllocatedBytes();
 
    private:
-    friend class ZonePool;
+    friend class ZoneStats;
     void ZoneReturned(Zone* zone);
 
     typedef std::map<Zone*, size_t> InitialValues;
 
-    ZonePool* const zone_pool_;
+    ZoneStats* const zone_stats_;
     InitialValues initial_values_;
     size_t total_allocated_bytes_at_start_;
     size_t max_allocated_bytes_;
 
     DISALLOW_COPY_AND_ASSIGN(StatsScope);
   };
 
-  explicit ZonePool(AccountingAllocator* allocator);
-  ~ZonePool();
+  explicit ZoneStats(AccountingAllocator* allocator);
+  ~ZoneStats();
 
   size_t GetMaxAllocatedBytes();
   size_t GetTotalAllocatedBytes();
   size_t GetCurrentAllocatedBytes();
 
  private:
   Zone* NewEmptyZone();
   void ReturnZone(Zone* zone);
 
   static const size_t kMaxUnusedSize = 3;
-  typedef std::vector<Zone*> Unused;
   typedef std::vector<Zone*> Used;
   typedef std::vector<StatsScope*> Stats;
 
-  Unused unused_;
   Used used_;
   Stats stats_;
   size_t max_allocated_bytes_;
   size_t total_deleted_bytes_;
   AccountingAllocator* allocator_;
 
-  DISALLOW_COPY_AND_ASSIGN(ZonePool);
+  DISALLOW_COPY_AND_ASSIGN(ZoneStats);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
-#endif
+#endif  // V8_COMPILER_ZONE_STATS_H_