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

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

Index: third_party/tcmalloc/chromium/src/base/commandlineflags.h
diff --git a/third_party/tcmalloc/chromium/src/base/commandlineflags.h b/third_party/tcmalloc/chromium/src/base/commandlineflags.h
index 649b95fa450e838832d65f0750161689c16a6bf4..6d41e8643659c560d4e9425f6da67bb556a0c403 100644
--- a/third_party/tcmalloc/chromium/src/base/commandlineflags.h
+++ b/third_party/tcmalloc/chromium/src/base/commandlineflags.h
@@ -119,6 +119,8 @@
 // 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
@@ -178,4 +180,14 @@ inline double EnvToDouble(const char* envname, double dflt) {
 
 #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_