Fix missing shadows for modal window

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
index 38a416bb19ca7db7b8690c143237c1cf8435b6c9..e188c22f8f4a092cfffba18fe94de92675696893 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
@@ -1359,9 +1359,13 @@ void DesktopWindowTreeHostX11::InitX11Window(
   if (swa.override_redirect)
     attribute_mask |= CWOverrideRedirect;
 
+  Widget* widget = native_widget_delegate_->AsWidget();
   const bool enable_transparent_visuals =
       params.type == Widget::InitParams::TYPE_DRAG ||
-      params.type == Widget::InitParams::TYPE_WINDOW;
+      (params.type == Widget::InitParams::TYPE_WINDOW &&
+       params.wm_role_name == "browser") ||
+      (params.type == Widget::InitParams::TYPE_WINDOW && !widget->IsModal() &&
+       params.opacity == Widget::InitParams::TRANSLUCENT_WINDOW);
 
   Visual* visual = CopyFromParent;
   int depth = CopyFromParent;