Adds Window::MoveChildToFront, with surrounding changes.

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 37e0752a9795056620410ac5f8a4eee6c1b7a5b3..6a0278d464005a4f9b911a69bae6959656f94257 100644
--- a/views/widget/native_widget_gtk.cc
+++ b/views/widget/native_widget_gtk.cc
@@ -1028,7 +1028,7 @@ void NativeWidgetGtk::CenterWindow(const gfx::Size& size) {
   gfx::Rect bounds(center_rect.x() + (center_rect.width() - size.width()) / 2,
                    center_rect.y() + (center_rect.height() - size.height()) / 2,
                    size.width(), size.height());
-  SetBoundsConstrained(bounds, NULL);
+  widget_->SetBoundsConstrained(bounds);
 }
 
 void NativeWidgetGtk::GetWindowPlacement(
@@ -1144,12 +1144,6 @@ void NativeWidgetGtk::SetSize(const gfx::Size& size) {
   }
 }
 
-void NativeWidgetGtk::SetBoundsConstrained(const gfx::Rect& bounds,
-                                           Widget* other_widget) {
-  // We apparently don't care about |other_widget|.
-  SetBounds(bounds);
-}
-
 void NativeWidgetGtk::MoveAbove(gfx::NativeView native_view) {
   ui::StackPopupWindow(GetNativeView(), native_view);
 }