corrected undefined behaviour when ptr is NULL in HeapFree

base/allocator/winheap_stubs_win.cc

 // Copyright 2016 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.
 
 // This code should move into the default Windows shim once the win-specific
 // allocation shim has been removed, and the generic shim has becaome the
 // default.
 
 #include "winheap_stubs_win.h"
 
@@ skipping 17 matching lines @@
 }
 
 }  // namespace
 
 void* WinHeapMalloc(size_t size) {
   if (size < kMaxWindowsAllocation)
     return HeapAlloc(get_heap_handle(), 0, size);
   return nullptr;
 }
 
-void WinHeapFree(void* size) {
-  HeapFree(get_heap_handle(), 0, size);
+void WinHeapFree(void* ptr) {
+  if (!ptr)
+    return;
+
+  HeapFree(get_heap_handle(), 0, ptr);
 }
 
 void* WinHeapRealloc(void* ptr, size_t size) {
   if (!ptr)
     return WinHeapMalloc(size);
   if (!size) {
     WinHeapFree(ptr);
     return nullptr;
   }
   if (size < kMaxWindowsAllocation)
@@ skipping 32 matching lines @@
   _PNH nh = _query_new_handler();
   if (!nh)
     return false;
   // Since exceptions are disabled, we don't really know if new_handler
   // failed.  Assume it will abort if it fails.
   return nh(size) ? true : false;
 }
 
 }  // namespace allocator
 }  // namespace base