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

ash/wm/workspace/workspace_window_resizer_unittest.cc

Index: ash/wm/workspace/workspace_window_resizer_unittest.cc
diff --git a/ash/wm/workspace/workspace_window_resizer_unittest.cc b/ash/wm/workspace/workspace_window_resizer_unittest.cc
index 0d8efc38411c8a4a2dee1253c31f5fd78979c71f..f43aebc133c6bb92ef9ffa5df3a9b46ec2f70763 100644
--- a/ash/wm/workspace/workspace_window_resizer_unittest.cc
+++ b/ash/wm/workspace/workspace_window_resizer_unittest.cc
@@ -650,7 +650,7 @@ TEST_F(WorkspaceWindowResizerTest, CancelSnapPhantom) {
   ASSERT_EQ(2U, root_windows.size());
 
   window_->SetBoundsInScreen(gfx::Rect(0, 0, 50, 60),
-                             Shell::GetScreen()->GetPrimaryDisplay());
+                             gfx::Screen::GetScreen()->GetPrimaryDisplay());
   EXPECT_EQ(root_windows[0], window_->GetRootWindow());
   EXPECT_FLOAT_EQ(1.0f, window_->layer()->opacity());
   {
@@ -795,7 +795,7 @@ TEST_F(WorkspaceWindowResizerTest, DontDragOffBottom) {
   Shell::GetInstance()->SetDisplayWorkAreaInsets(
       Shell::GetPrimaryRootWindow(), gfx::Insets(0, 0, 10, 0));
 
-  ASSERT_EQ(1, Shell::GetScreen()->GetNumDisplays());
+  ASSERT_EQ(1, gfx::Screen::GetScreen()->GetNumDisplays());
 
   window_->SetBounds(gfx::Rect(100, 200, 300, 400));
   scoped_ptr<WindowResizer> resizer(CreateResizerForTest(
@@ -814,7 +814,7 @@ TEST_F(WorkspaceWindowResizerTest, DontDragOffBottomWithMultiDisplay) {
     return;
 
   UpdateDisplay("800x600,800x600");
-  ASSERT_EQ(2, Shell::GetScreen()->GetNumDisplays());
+  ASSERT_EQ(2, gfx::Screen::GetScreen()->GetNumDisplays());
 
   Shell::GetInstance()->SetDisplayWorkAreaInsets(
       Shell::GetPrimaryRootWindow(), gfx::Insets(0, 0, 10, 0));