remove redundant ifdefs

third_party/tcmalloc/chromium/src/system-alloc.cc

 // 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 82 matching lines @@
 // Check that no bit is set at position ADDRESS_BITS or higher.
 template <int ADDRESS_BITS> bool CheckAddressBits(uintptr_t ptr) {
   return (ptr >> ADDRESS_BITS) == 0;
 }
 
 // Specialize for the bit width of a pointer to avoid undefined shift.
 template <> bool CheckAddressBits<8 * sizeof(void*)>(uintptr_t ptr) {
   return true;
 }
 
-#if (defined(OS_LINUX) || defined(OS_CHROMEOS)) && defined(__x86_64__)
+#if defined(OS_LINUX) && defined(__x86_64__)
 #define ASLR_IS_SUPPORTED
 #endif
 
 #if defined(ASLR_IS_SUPPORTED)
 // From libdieharder, public domain library by Bob Jenkins (rngav.c).
 // Described at http://burtleburtle.net/bob/rand/smallprng.html.
 // Not cryptographically secure, but good enough for what we need.
 typedef uint32_t u4;
 struct ranctx {
   u4 a;
@@ skipping 572 matching lines @@
     }
   }
 #endif
 }
 
 void TCMalloc_SystemCommit(void* start, size_t length) {
   // Nothing to do here.  TCMalloc_SystemRelease does not alter pages
   // such that they need to be re-committed before they can be used by the
   // application.
 }