Moved zones and zone related stuff in its own directory.

src/zone/zone-segment.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_ZONE_SEGMENT_H_
+#define V8_ZONE_ZONE_SEGMENT_H_
+
+#include "src/v8.h"
+
+// Segments represent chunks of memory: They have starting address
+// (encoded in the this pointer) and a size in bytes. Segments are
+// chained together forming a LIFO structure with the newest segment
+// available as segment_head_. Segments are allocated using malloc()
+// and de-allocated using free().
+namespace v8 {
+namespace internal {
+
+//  Forward declaration
+class Zone;
+
+class Segment {
+ public:
+  void Initialize(Segment* next, size_t size, Zone* zone) {
+    next_ = next;
+    size_ = size;
+    zone_ = zone;
+  }
+
+  Zone* zone() const { return zone_; }
+  void set_zone(Zone* const zone) { zone_ = zone; }
+
+  Segment* next() const { return next_; }
+  void set_next(Segment* const next) { next_ = next; }
+
+  size_t size() const { return size_; }
+  size_t capacity() const { return size_ - sizeof(Segment); }
+
+  Address start() const { return address(sizeof(Segment)); }
+  Address end() const { return address(size_); }
+
+ private:
+  // Computes the address of the nth byte in this segment.
+  Address address(size_t n) const { return Address(this) + n; }
+
+  Zone* zone_;
+  Segment* next_;
+  size_t size_;
+};
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_ZONE_ZONE_SEGMENT_H_