Landing http://codereview.chromium.org/7033062/:

third_party/tcmalloc/chromium/src/memory_region_map.cc

Index: third_party/tcmalloc/chromium/src/memory_region_map.cc
===================================================================
--- third_party/tcmalloc/chromium/src/memory_region_map.cc	(revision 88314)
+++ third_party/tcmalloc/chromium/src/memory_region_map.cc	(working copy)
@@ -628,9 +628,9 @@
   }
 }
 
-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) {