diff --git a/src/base/commandlineflags.h b/src/base/commandlineflags.h
new file mode 100644
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+++ b/src/base/commandlineflags.h
@@ -0,0 +1,166 @@
+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+// Copyright (c) 2005, 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.
+
+// ---
+// This file is a compatibility layer that defines Google's version of
+// command line flags that are used for configuration.
+//
+// We put flags into their own namespace.  It is purposefully
+// named in an opaque way that people should have trouble typing
+// directly.  The idea is that DEFINE puts the flag in the weird
+// namespace, and DECLARE imports the flag from there into the
+// current namespace.  The net result is to force people to use
+// DECLARE to get access to a flag, rather than saying
+//   extern bool FLAGS_logtostderr;
+// or some such instead.  We want this so we can put extra
+// functionality (like sanity-checking) in DECLARE if we want,
+// and make sure it is picked up everywhere.
+//
+// We also put the type of the variable in the namespace, so that
+// people can't DECLARE_int32 something that they DEFINE_bool'd
+// elsewhere.
+#ifndef BASE_COMMANDLINEFLAGS_H_
+#define BASE_COMMANDLINEFLAGS_H_
+
+#include <config.h>
+#include <string>
+#include <string.h>               // for memchr
+#include <stdlib.h>               // for getenv
+#include "base/basictypes.h"
+
+#define DECLARE_VARIABLE(type, name)                                          \
+  namespace FLAG__namespace_do_not_use_directly_use_DECLARE_##type##_instead {  \
+  extern PERFTOOLS_DLL_DECL type FLAGS_##name;                                \
+  }                                                                           \
+  using FLAG__namespace_do_not_use_directly_use_DECLARE_##type##_instead::FLAGS_##name
+
+#define DEFINE_VARIABLE(type, name, value, meaning) \
+  namespace FLAG__namespace_do_not_use_directly_use_DECLARE_##type##_instead {  \
+  PERFTOOLS_DLL_DECL type FLAGS_##name(value);                                \
+  char FLAGS_no##name;                                                        \
+  }                                                                           \
+  using FLAG__namespace_do_not_use_directly_use_DECLARE_##type##_instead::FLAGS_##name
+
+// bool specialization
+#define DECLARE_bool(name) \
+  DECLARE_VARIABLE(bool, name)
+#define DEFINE_bool(name, value, meaning) \
+  DEFINE_VARIABLE(bool, name, value, meaning)
+
+// int32 specialization
+#define DECLARE_int32(name) \
+  DECLARE_VARIABLE(int32, name)
+#define DEFINE_int32(name, value, meaning) \
+  DEFINE_VARIABLE(int32, name, value, meaning)
+
+// int64 specialization
+#define DECLARE_int64(name) \
+  DECLARE_VARIABLE(int64, name)
+#define DEFINE_int64(name, value, meaning) \
+  DEFINE_VARIABLE(int64, name, value, meaning)
+
+#define DECLARE_uint64(name) \
+  DECLARE_VARIABLE(uint64, name)
+#define DEFINE_uint64(name, value, meaning) \
+  DEFINE_VARIABLE(uint64, name, value, meaning)
+
+// double specialization
+#define DECLARE_double(name) \
+  DECLARE_VARIABLE(double, name)
+#define DEFINE_double(name, value, meaning) \
+  DEFINE_VARIABLE(double, name, value, meaning)
+
+// Special case for string, because we have to specify the namespace
+// std::string, which doesn't play nicely with our FLAG__namespace hackery.
+#define DECLARE_string(name)                                          \
+  namespace FLAG__namespace_do_not_use_directly_use_DECLARE_string_instead {  \
+  extern std::string FLAGS_##name;                                                   \
+  }                                                                           \
+  using FLAG__namespace_do_not_use_directly_use_DECLARE_string_instead::FLAGS_##name
+#define DEFINE_string(name, value, meaning) \
+  namespace FLAG__namespace_do_not_use_directly_use_DECLARE_string_instead {  \
+  std::string FLAGS_##name(value);                                                   \
+  char FLAGS_no##name;                                                        \
+  }                                                                           \
+  using FLAG__namespace_do_not_use_directly_use_DECLARE_string_instead::FLAGS_##name
+
+// implemented in sysinfo.cc
+namespace tcmalloc {
+  namespace commandlineflags {
+
+    inline bool StringToBool(const char *value, bool def) {
+      if (!value) {
+        return def;
+      }
+      return memchr("tTyY1\0", value[0], 6) != NULL;
+    }
+
+    inline int StringToInt(const char *value, int def) {
+      if (!value) {
+        return def;
+      }
+      return strtol(value, NULL, 10);
+    }
+
+    inline long long StringToLongLong(const char *value, long long def) {
+      if (!value) {
+        return def;
+      }
+      return strtoll(value, NULL, 10);
+    }
+
+    inline double StringToDouble(const char *value, double def) {
+      if (!value) {
+        return def;
+      }
+      return strtod(value, NULL);
+    }
+  }
+}
+
+// These macros (could be functions, but I don't want to bother with a .cc
+// file), make it easier to initialize flags from the environment.
+
+#define EnvToString(envname, dflt)   \
+  (!getenv(envname) ? (dflt) : getenv(envname))
+
+#define EnvToBool(envname, dflt)   \
+  tcmalloc::commandlineflags::StringToBool(getenv(envname), dflt)
+
+#define EnvToInt(envname, dflt)  \
+  tcmalloc::commandlineflags::StringToInt(getenv(envname), dflt)
+
+#define EnvToInt64(envname, dflt)  \
+  tcmalloc::commandlineflags::StringToLongLong(getenv(envname), dflt)
+
+#define EnvToDouble(envname, dflt)  \
+  tcmalloc::commandlineflags::StringToDouble(getenv(envname), dflt)
+
+#endif  // BASE_COMMANDLINEFLAGS_H_