diff --git a/src/stack_trace_table.h b/src/stack_trace_table.h
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+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+// Copyright (c) 2009, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// ---
+// Author: Andrew Fikes
+//
+// Utility class for coalescing sampled stack traces.  Not thread-safe.
+
+#ifndef TCMALLOC_STACK_TRACE_TABLE_H_
+#define TCMALLOC_STACK_TRACE_TABLE_H_
+
+#include <config.h>
+#ifdef HAVE_STDINT_H
+#include <stdint.h>                     // for uintptr_t
+#endif
+#include "common.h"
+
+namespace tcmalloc {
+
+class PERFTOOLS_DLL_DECL StackTraceTable {
+ public:
+  // REQUIRES: L < pageheap_lock
+  StackTraceTable();
+  ~StackTraceTable();
+
+  // Adds stack trace "t" to table.
+  //
+  // REQUIRES: L >= pageheap_lock
+  void AddTrace(const StackTrace& t);
+
+  // Returns stack traces formatted per MallocExtension guidelines.
+  // May return NULL on error.  Clears state before returning.
+  //
+  // REQUIRES: L < pageheap_lock
+  void** ReadStackTracesAndClear();
+
+  // Exposed for PageHeapAllocator
+  struct Bucket {
+    // Key
+    uintptr_t hash;
+    StackTrace trace;
+
+    // Payload
+    int count;
+    Bucket* next;
+
+    bool KeyEqual(uintptr_t h, const StackTrace& t) const;
+  };
+
+  // For testing
+  int depth_total() const { return depth_total_; }
+  int bucket_total() const { return bucket_total_; }
+
+ private:
+  static const int kHashTableSize = 1 << 14; // => table_ is 128k
+
+  bool error_;
+  int depth_total_;
+  int bucket_total_;
+  Bucket** table_;
+};
+
+}  // namespace tcmalloc
+
+#endif  // TCMALLOC_STACK_TRACE_TABLE_H_