[NOT TO COMMIT!] Merge Chromium-specific changes in tcmalloc thru. the original gperftools r136.

third_party/tcmalloc/chromium/src/memory_region_map.cc

Index: third_party/tcmalloc/chromium/src/memory_region_map.cc
diff --git a/third_party/tcmalloc/chromium/src/memory_region_map.cc b/third_party/tcmalloc/chromium/src/memory_region_map.cc
index e281706b929faa5021106612c2c0157d44ae474a..15ef2b29127e02349b3e6e9d5a0b1145fe33ab61 100644
--- a/third_party/tcmalloc/chromium/src/memory_region_map.cc
+++ b/third_party/tcmalloc/chromium/src/memory_region_map.cc
@@ -618,9 +618,9 @@ void MemoryRegionMap::MremapHook(const void* result,
   }
 }
 
-extern "C" void* __sbrk(ptrdiff_t increment);  // defined in libc
+extern "C" void* __sbrk(std::ptrdiff_t increment);  // defined in libc
 
-void MemoryRegionMap::SbrkHook(const void* result, ptrdiff_t increment) {
+void MemoryRegionMap::SbrkHook(const void* result, std::ptrdiff_t increment) {
   RAW_VLOG(10, "Sbrk = 0x%"PRIxPTR" of %"PRIdS"", (uintptr_t)result, increment);
   if (result != reinterpret_cast<void*>(-1)) {
     if (increment > 0) {