Stack at top functionality for Aura-based windows

ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
index b9087c324ecc234c67fb36f7a0460574da31ab16..29eb6d117feded5856150025f971fb71134edb86 100644
--- a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
@@ -352,6 +352,10 @@ void DesktopRootWindowHostX11::SetSize(const gfx::Size& size) {
   NOTIMPLEMENTED();
 }
 
+void DesktopRootWindowHostX11::StackAtTop() {
+  XRaiseWindow(xdisplay_, xwindow_);
+}
+
 void DesktopRootWindowHostX11::CenterWindow(const gfx::Size& size) {
   gfx::Rect parent_bounds = GetWorkAreaBoundsInScreen();