Add context to gfx::Screen calls in support of simultaneous desktop+ash

ash/wm/window_util.cc

Index: ash/wm/window_util.cc
diff --git a/ash/wm/window_util.cc b/ash/wm/window_util.cc
index b4c2a4d398fb8c65fd984ff535f3f081f4c4d321..8cc1c1f7814f373c8cd4bc11879566260e917b94 100644
--- a/ash/wm/window_util.cc
+++ b/ash/wm/window_util.cc
@@ -108,7 +108,8 @@ void ToggleMaximizedWindow(aura::Window* window) {
 }
 
 void CenterWindow(aura::Window* window) {
-  const gfx::Display display = gfx::Screen::GetDisplayNearestWindow(window);
+  const gfx::Display display =
+      Shell::GetAshScreen()->GetDisplayNearestWindow(window);
   gfx::Rect center = display.work_area().Center(window->bounds().size());
   window->SetBounds(center);
 }