Add UIControlsAsh that works with multiple root windows

ash/shell_factory.h

Index: ash/shell_factory.h
diff --git a/ash/shell_factory.h b/ash/shell_factory.h
index f18c57af4a395f8a95f1d98b4b22b47256b9d852..59b20a92354020af8c5b6bb332b3214e62338216 100644
--- a/ash/shell_factory.h
+++ b/ash/shell_factory.h
@@ -17,6 +17,10 @@ namespace gfx {
 class ImageSkia;
 }
 
+namespace ui_controls {
+class UIControlsAura;
+}
+
 namespace views {
 class View;
 class Widget;
@@ -30,7 +34,10 @@ namespace internal {
 void CreateDesktopBackground(const gfx::ImageSkia& wallpaper,
                              WallpaperLayout wallpaper_layout,
                              aura::RootWindow* root_window);
+
 ASH_EXPORT views::Widget* CreateStatusArea(views::View* contents);
+
+ui_controls::UIControlsAura* CreateUIControls();
 }  // namespace internal
 
 }  // namespace ash