Fix realloc to not call the new_handler (which is for failures)...

third_party/tcmalloc/allocator_shim.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <config.h>
 
 // When defined, different heap allocators can be used via an environment
 // variable set before running the program.  This may reduce the amount
 // of inlining that we get with malloc/free/etc.  Disabling makes it
 // so that only tcmalloc can be used.
@@ skipping 142 matching lines @@
         break;
       case TCMALLOC:
       default:
         new_ptr = do_realloc(ptr, size);
         break;
     }
 #else
     // TCMalloc case.
     new_ptr = do_realloc(ptr, size);
 #endif
-    if (new_ptr)
+
+    // Subtle warning:  NULL return does not alwas indicate out-of-memory.  If
+    // the requested new size is zero, realloc should free the ptr and return
+    // NULL.
+    if (new_ptr || !size)
       return new_ptr;
     if (!new_mode || !call_new_handler(true))
       break;
   }
   return new_ptr;
 }
 
 // TODO(mbelshe): Implement this for other allocators.
 void malloc_stats(void) __THROW {
 #ifdef ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
@@ skipping 73 matching lines @@
 // to test whether the CRT has been initialized.  Once we've ripped out
 // the allocators from libcmt, we need to provide this definition so that
 // the rest of the CRT is still usable.
 extern "C" void* _crtheap = reinterpret_cast<void*>(1);
 
 #endif  // WIN32
 
 #include "generic_allocators.cc"
 
 }  // extern C