Add View::ReorderChildView and Widget::MoveToTop.

views/widget/native_widget_gtk.cc

Index: views/widget/native_widget_gtk.cc
diff --git a/views/widget/native_widget_gtk.cc b/views/widget/native_widget_gtk.cc
index 74795e9a99d25ac78578fab472d5e9bfb9548f52..6bd760c74b3532737efee2f7963ef387a8a4ad93 100644
--- a/views/widget/native_widget_gtk.cc
+++ b/views/widget/native_widget_gtk.cc
@@ -1062,6 +1062,11 @@ void NativeWidgetGtk::MoveAbove(gfx::NativeView native_view) {
   ui::StackPopupWindow(GetNativeView(), native_view);
 }
 
+void NativeWidgetGtk::MoveToTop() {
+  DCHECK(GTK_IS_WINDOW(GetNativeView()));
+  gtk_window_present(GTK_WINDOW(GetNativeView()));
+}
+
 void NativeWidgetGtk::SetShape(gfx::NativeRegion region) {
   if (widget_ && widget_->window) {
     gdk_window_shape_combine_region(widget_->window, region, 0, 0);