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

ash/shelf/overflow_bubble_view.cc

Index: ash/shelf/overflow_bubble_view.cc
diff --git a/ash/shelf/overflow_bubble_view.cc b/ash/shelf/overflow_bubble_view.cc
index 7dae49a536995cb82cc6ce59004807ea9afdd165..5273e50684bdde0e6c1e5342a97d60b663a4927c 100644
--- a/ash/shelf/overflow_bubble_view.cc
+++ b/ash/shelf/overflow_bubble_view.cc
@@ -111,8 +111,10 @@ void OverflowBubbleView::ScrollByYOffset(int y_offset) {
 gfx::Size OverflowBubbleView::GetPreferredSize() const {
   gfx::Size preferred_size = GetContentsSize();
 
-  const gfx::Rect monitor_rect = Shell::GetScreen()->GetDisplayNearestPoint(
-      GetAnchorRect().CenterPoint()).work_area();
+  const gfx::Rect monitor_rect =
+      gfx::Screen::GetScreen()
+          ->GetDisplayNearestPoint(GetAnchorRect().CenterPoint())
+          .work_area();
   if (!monitor_rect.IsEmpty()) {
     if (IsHorizontalAlignment()) {
       preferred_size.set_width(std::min(
@@ -194,8 +196,10 @@ gfx::Rect OverflowBubbleView::GetBubbleBounds() {
       content_size,
       false);
 
-  gfx::Rect monitor_rect = Shell::GetScreen()->GetDisplayNearestPoint(
-      anchor_rect.CenterPoint()).work_area();
+  gfx::Rect monitor_rect =
+      gfx::Screen::GetScreen()
+          ->GetDisplayNearestPoint(anchor_rect.CenterPoint())
+          .work_area();
 
   int offset = 0;
   if (views::BubbleBorder::is_arrow_on_horizontal(arrow())) {