Remove now-unnecessary wrappers around gfx::Screen::GetScreen()

ash/wm/immersive_fullscreen_controller.cc

Index: ash/wm/immersive_fullscreen_controller.cc
diff --git a/ash/wm/immersive_fullscreen_controller.cc b/ash/wm/immersive_fullscreen_controller.cc
index 538323687091efaca6f609dd17e7526dd97290da..7d0a85157fec38be45eda71a8fb24878fca3f302 100644
--- a/ash/wm/immersive_fullscreen_controller.cc
+++ b/ash/wm/immersive_fullscreen_controller.cc
@@ -99,7 +99,7 @@ gfx::Point GetEventLocationInScreen(const ui::LocatedEvent& event) {
 
 // Returns the bounds of the display nearest to |window| in screen coordinates.
 gfx::Rect GetDisplayBoundsInScreen(aura::Window* window) {
-  return Shell::GetScreen()->GetDisplayNearestWindow(window).bounds();
+  return gfx::Screen::GetScreen()->GetDisplayNearestWindow(window).bounds();
 }
 
 }  // namespace
@@ -926,7 +926,7 @@ bool ImmersiveFullscreenController::ShouldHandleGestureEvent(
   // closest screen ensures that the event is from a valid bezel (as opposed to
   // another screen in an extended desktop).
   gfx::Rect screen_bounds =
-      Shell::GetScreen()->GetDisplayNearestPoint(location).bounds();
+      gfx::Screen::GetScreen()->GetDisplayNearestPoint(location).bounds();
   return (!screen_bounds.Contains(location) &&
           location.y() < hit_bounds_in_screen.y() &&
           location.x() >= hit_bounds_in_screen.x() &&