Count m(un)map for each stacktrace in MemoryRegionMap instead of HeapProfileTable.

third_party/tcmalloc/chromium/src/heap-profile-stats.h

+// Copyright (c) 2013 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.
+
+// This file defines structs to accumulate memory allocation and deallocation
+// counts.  These structs are commonly used for malloc (in HeapProfileTable)
+// and mmap (in MemoryRegionMap).
+
+#ifndef HEAP_PROFILE_STATS_H_
+#define HEAP_PROFILE_STATS_H_
+
+struct HeapProfileStats {
+  int32 allocs;      // Number of allocation calls.

[Alexander Potapenko, 2013/03/07 14:50:52]

Again, methods before members and DISALLOW_COPY_AND_ASSIGN (if needed), please.

[Dai Mikurube (NOT FULLTIME), 2013/03/07 17:14:24]

Reordered.  And, I don't add DISALLOW_COPY_AND_ASSIGN for this since this struct
comes from the original TCMalloc, and it doesn't have.

+  int32 frees;       // Number of free calls.
+  int64 alloc_size;  // Total size of all allocated objects so far.
+  int64 free_size;   // Total size of all freed objects so far.
+
+  // Returns true if the two HeapProfileStats are semantically equal.
+  bool Equivalent(const HeapProfileStats& x) const {
+    return allocs - frees == x.allocs - x.frees &&
+      alloc_size - free_size == x.alloc_size - x.free_size;
+  }
+};
+
+// Allocation and deallocation statistics per each stack trace.
+struct HeapProfileBucket : public HeapProfileStats {
+  // Longest stack trace we record.
+  static const int kMaxStackDepth = 32;
+
+  uintptr_t hash;           // Hash value of the stack trace.
+  int depth;                // Depth of stack trace.
+  const void** stack;       // Stack trace.
+  HeapProfileBucket* next;  // Next entry in hash-table.
+};
+
+#endif  // HEAP_PROFILE_STATS_H_