views: don't use open-folder icons in TreeView on Mac

ui/views/controls/tree/tree_view.cc

Index: ui/views/controls/tree/tree_view.cc
diff --git a/ui/views/controls/tree/tree_view.cc b/ui/views/controls/tree/tree_view.cc
index fc7541924357eb2a0649309263639ff93ba80bb3..2bfbd21089c14a2869b6131ccf4cbc1ff121e31a 100644
--- a/ui/views/controls/tree/tree_view.cc
+++ b/ui/views/controls/tree/tree_view.cc
@@ -780,7 +780,7 @@ void TreeView::PaintRow(gfx::Canvas* canvas,
   int icon_index = model_->GetIconIndex(node->model_node());
   if (icon_index != -1)
     icon = icons_[icon_index];
-  else if (node == selected_node_)
+  else if (node == selected_node_ && PlatformStyle::kTreeViewUsesOpenIcon)
     icon = open_icon_;
   else
     icon = closed_icon_;