Revert of Fix icon on Windows XP taskbar

ui/views/win/hwnd_message_handler.cc

Index: ui/views/win/hwnd_message_handler.cc
diff --git a/ui/views/win/hwnd_message_handler.cc b/ui/views/win/hwnd_message_handler.cc
index f2abb6b33d07d36477c04fb297521c545ffebade..f35b155db25513a71dfb8c5e8835bf652f049fe0 100644
--- a/ui/views/win/hwnd_message_handler.cc
+++ b/ui/views/win/hwnd_message_handler.cc
@@ -905,16 +905,9 @@
 
 HICON HWNDMessageHandler::GetDefaultWindowIcon() const {
   if (use_system_default_icon_)
-    return nullptr;
+    return NULL;
   return ViewsDelegate::views_delegate ?
-      ViewsDelegate::views_delegate->GetDefaultWindowIcon() : nullptr;
-}
-
-HICON HWNDMessageHandler::GetSmallWindowIcon() const {
-  if (use_system_default_icon_)
-    return nullptr;
-  return ViewsDelegate::views_delegate ?
-      ViewsDelegate::views_delegate->GetSmallWindowIcon() : nullptr;
+      ViewsDelegate::views_delegate->GetDefaultWindowIcon() : NULL;
 }
 
 LRESULT HWNDMessageHandler::OnWndProc(UINT message,