Don't let tcmalloc read all kinds of env vars at startup.

third_party/tcmalloc/chromium/src/base/commandlineflags.h

 // 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
@@ skipping 101 matching lines @@
   std::string FLAGS_##name(value);                                                   \
   char FLAGS_no##name;                                                        \
   }                                                                           \
   using FLAG__namespace_do_not_use_directly_use_DECLARE_string_instead::FLAGS_##name
 
 // 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.
 // They are functions in Android because __system_property_get() doesn't
 // return a string.
 
+#if defined(ENABLE_PROFILING)
+
 #if defined(__ANDROID__) || defined(ANDROID)
 
 // Returns a pointer to a static variable.  The string pointed by the returned
 // pointer must not be modified.
 inline const char* const EnvToString(const char* envname, const char* dflt) {
   static char system_property_value[PROP_VALUE_MAX];
   if (__system_property_get(envname, system_property_value) > 0)
     return system_property_value;
   return dflt;
 }
@@ skipping 39 matching lines @@
   (!getenv(envname) ? (dflt) : strtol(getenv(envname), NULL, 10))
 
 #define EnvToInt64(envname, dflt)  \
   (!getenv(envname) ? (dflt) : strtoll(getenv(envname), NULL, 10))
 
 #define EnvToDouble(envname, dflt)  \
   (!getenv(envname) ? (dflt) : strtod(getenv(envname), NULL))
 
 #endif  // defined(__ANDROID__) || defined(ANDROID)
 
+#else  // defined(ENABLE_PROFILING)
+
+#define EnvToString(envname, dflt) (dflt)
+#define EnvToBool(envname, dflt) (dflt)
+#define EnvToInt(envname, dflt) (dflt)
+#define EnvToInt64(envname, dflt) (dflt)
+#define EnvToDouble(envname, dflt) (dflt)
+
+#endif  // defined(ENABLE_PROFILING)
+
 #endif  // BASE_COMMANDLINEFLAGS_H_