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

ash/wm/window_manager_unittest.cc

Index: ash/wm/window_manager_unittest.cc
diff --git a/ash/wm/window_manager_unittest.cc b/ash/wm/window_manager_unittest.cc
index 5bad49d732d104fafa93dc203ce9cbb7f1497ec8..14e9cb2617d8ffc4cb2f1643e41d46ccaadcf945 100644
--- a/ash/wm/window_manager_unittest.cc
+++ b/ash/wm/window_manager_unittest.cc
@@ -603,8 +603,10 @@ TEST_F(WindowManagerTest, MAYBE_TransformActivate) {
   aura::Window* root_window = Shell::GetPrimaryRootWindow();
   gfx::Size size = root_window->bounds().size();
   EXPECT_EQ(gfx::Rect(size).ToString(),
-            Shell::GetScreen()->GetDisplayNearestPoint(
-                gfx::Point()).bounds().ToString());
+            gfx::Screen::GetScreen()
+                ->GetDisplayNearestPoint(gfx::Point())
+                .bounds()
+                .ToString());
 
   // Rotate it clock-wise 90 degrees.
   gfx::Transform transform;