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

ash/display/screen_ash_unittest.cc

Index: ash/display/screen_ash_unittest.cc
diff --git a/ash/display/screen_ash_unittest.cc b/ash/display/screen_ash_unittest.cc
index 798b5e6a048d951d804a166a6dbb4da6f6f05944..a60d54fba20cefd10ecf4b882a54d74a475d6b26 100644
--- a/ash/display/screen_ash_unittest.cc
+++ b/ash/display/screen_ash_unittest.cc
@@ -15,8 +15,6 @@ class ScreenAshTest : public test::AshTestBase {
   ScreenAshTest() {}
   ~ScreenAshTest() override {}
 
-  static gfx::Screen* Screen() { return Shell::GetScreen(); }
-
  private:
   DISALLOW_COPY_AND_ASSIGN(ScreenAshTest);
 };
@@ -38,8 +36,10 @@ TEST_F(ScreenAshTest, TestGetWindowAtScreenPoint) {
 
   ASSERT_NE(win1->GetRootWindow(), win2->GetRootWindow());
 
-  EXPECT_EQ(win1.get(), Screen()->GetWindowAtScreenPoint(gfx::Point(50, 60)));
-  EXPECT_EQ(win2.get(), Screen()->GetWindowAtScreenPoint(gfx::Point(250, 260)));
+  EXPECT_EQ(win1.get(), gfx::Screen::GetScreen()->GetWindowAtScreenPoint(
+                            gfx::Point(50, 60)));
+  EXPECT_EQ(win2.get(), gfx::Screen::GetScreen()->GetWindowAtScreenPoint(
+                            gfx::Point(250, 260)));
 }
 
 }  // namespace ash