Add desktop vs. ash context to ui_controls

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index db4b5c0b84578ac8c5ead64f9ee65ad8368e9cba..98a0ea2023b1efb7f4065d8f8441986e6ccf70f5 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -50,6 +50,9 @@ class Rect;
 namespace ui {
 class Layer;
 }
+namespace ui_controls {
+class UIControls;
+}
 namespace views {
 class NonClientFrameView;
 class Widget;
@@ -459,6 +462,8 @@ class ASH_EXPORT Shell : internal::SystemModalContainerEventFilterDelegate,
 
   ScreenAsh* screen_;
 
+  scoped_ptr<ui_controls::UIControls> ui_controls_;
+
   // Active root window. Never becomes NULL during the session.
   aura::RootWindow* active_root_window_;