Move WindowModalityController to CoreWm.

ash/shell.h

Index: ash/shell.h
===================================================================
--- ash/shell.h	(revision 170620)
+++ ash/shell.h	(working copy)
@@ -58,6 +58,7 @@
 class InputMethodEventFilter;
 class ShadowController;
 class VisibilityController;
+class WindowModalityController;
 }
 }
 
@@ -110,7 +111,6 @@
 class SystemModalContainerEventFilter;
 class TooltipController;
 class TouchObserverHUD;
-class WindowModalityController;
 class WorkspaceController;
 }
 
@@ -488,11 +488,12 @@
   scoped_ptr<aura::client::StackingClient> stacking_client_;
   scoped_ptr<internal::ActivationController> activation_controller_;
   scoped_ptr<internal::CaptureController> capture_controller_;
-  scoped_ptr<internal::WindowModalityController> window_modality_controller_;
   scoped_ptr<internal::DragDropController> drag_drop_controller_;
   scoped_ptr<internal::ResizeShadowController> resize_shadow_controller_;
   scoped_ptr<views::corewm::ShadowController> shadow_controller_;
   scoped_ptr<views::corewm::VisibilityController> visibility_controller_;
+  scoped_ptr<views::corewm::WindowModalityController>
+      window_modality_controller_;
   scoped_ptr<internal::TooltipController> tooltip_controller_;
   scoped_ptr<DesktopBackgroundController> desktop_background_controller_;
   scoped_ptr<PowerButtonController> power_button_controller_;