Replaced ptrdiff_t with std::ptrdiff_t in all files to enable build with gcc-4.6.0.

third_party/tcmalloc/chromium/src/heap-checker.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 2115 matching lines @@
                                    int flags,
                                    int fd,
                                    off_t offset) {
   InitHeapLeakCheckerFromMallocHook();
   // record this first mmap as well (if we need to):
   MallocHook::InvokeMmapHook(
     result, start, size, protection, flags, fd, offset);
 }
 
 // Important to have this to catch the first sbrk call (say from tcmalloc):
-extern void InitialMallocHook_Sbrk(const void* result, ptrdiff_t increment) {
+extern void InitialMallocHook_Sbrk(const void* result, std::ptrdiff_t increment) {
   InitHeapLeakCheckerFromMallocHook();
   // record this first sbrk as well (if we need to):
   MallocHook::InvokeSbrkHook(result, increment);
 }
 
 // static
 void CancelInitialMallocHooks() {
   if (MallocHook::GetNewHook() == InitialMallocHook_New) {
     MallocHook::SetNewHook(NULL);
   }
@@ skipping 234 matching lines @@
 // static
 const void* HeapLeakChecker::GetAllocCaller(void* ptr) {
   // this is used only in the unittest, so the heavy checks are fine
   HeapProfileTable::AllocInfo info;
   { SpinLockHolder l(&heap_checker_lock);
     RAW_CHECK(heap_profile->FindAllocDetails(ptr, &info), "");
   }
   RAW_CHECK(info.stack_depth >= 1, "");
   return info.call_stack[0];
 }