corrected undefined behaviour when ptr is NULL in HeapFree

base/allocator/winheap_stubs_win.cc

Index: base/allocator/winheap_stubs_win.cc
diff --git a/base/allocator/winheap_stubs_win.cc b/base/allocator/winheap_stubs_win.cc
index 7298bb9411ad3601df13ce512b6f20281f4756a9..593e386ed9e741c97168d47bff391fdad44d7993 100644
--- a/base/allocator/winheap_stubs_win.cc
+++ b/base/allocator/winheap_stubs_win.cc
@@ -35,8 +35,11 @@ void* WinHeapMalloc(size_t 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) {