Tweak TCMalloc freelist pointer masking

third_party/tcmalloc/chromium/src/free_list.cc

Index: third_party/tcmalloc/chromium/src/free_list.cc
===================================================================
--- third_party/tcmalloc/chromium/src/free_list.cc	(revision 165409)
+++ third_party/tcmalloc/chromium/src/free_list.cc	(working copy)
@@ -83,11 +83,8 @@
 inline void* MaskPtr(void* p) {
   // Maximize ASLR entropy and guarantee the result is an invalid address.
   const uintptr_t mask = ~(reinterpret_cast<uintptr_t>(TCMalloc_SystemAlloc)
-                           >> 13) | 1;
-  // Do not mask NULL pointers, otherwise we could leak address state.
-  if (p)
-    return reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(p) ^ mask);
-  return p;
+                           >> 13);
+  return reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(p) ^ mask);
 }
 
 inline void* UnmaskPtr(void* p) {