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

ash/wm/dock/docked_window_layout_manager.cc

Index: ash/wm/dock/docked_window_layout_manager.cc
diff --git a/ash/wm/dock/docked_window_layout_manager.cc b/ash/wm/dock/docked_window_layout_manager.cc
index 653d09af395d57f7642d35ca7c94cd4791e77233..d79bcaccadb6303f994bcb657ae3b8ad2d708236 100644
--- a/ash/wm/dock/docked_window_layout_manager.cc
+++ b/ash/wm/dock/docked_window_layout_manager.cc
@@ -614,8 +614,9 @@ bool DockedWindowLayoutManager::CanDockWindow(
   }
   // If a window is tall and cannot be resized down to maximum height allowed
   // then it cannot be docked.
-  const gfx::Rect work_area =
-      Shell::GetScreen()->GetDisplayNearestWindow(dock_container_).work_area();
+  const gfx::Rect work_area = gfx::Screen::GetScreen()
+                                  ->GetDisplayNearestWindow(dock_container_)
+                                  .work_area();
   if (GetWindowHeightCloseTo(window, work_area.height()) > work_area.height())
     return false;
   // Cannot dock on the other size from an existing dock.
@@ -932,8 +933,9 @@ void DockedWindowLayoutManager::OnWindowActivated(
 void DockedWindowLayoutManager::MaybeMinimizeChildrenExcept(
     aura::Window* child) {
   // Minimize any windows that don't fit without overlap.
-  const gfx::Rect work_area =
-      Shell::GetScreen()->GetDisplayNearestWindow(dock_container_).work_area();
+  const gfx::Rect work_area = gfx::Screen::GetScreen()
+                                  ->GetDisplayNearestWindow(dock_container_)
+                                  .work_area();
   int available_room = work_area.height();
   bool gap_needed = !!child;
   if (child)
@@ -978,8 +980,8 @@ void DockedWindowLayoutManager::RestoreDockedWindow(
   // Always place restored window at the bottom shuffling the other windows up.
   // TODO(varkha): add a separate container for docked windows to keep track
   // of ordering.
-  gfx::Display display = Shell::GetScreen()->GetDisplayNearestWindow(
-      dock_container_);
+  gfx::Display display =
+      gfx::Screen::GetScreen()->GetDisplayNearestWindow(dock_container_);
   const gfx::Rect work_area = display.work_area();
 
   // Evict the window if it can no longer be docked because of its height.
@@ -1112,8 +1114,9 @@ void DockedWindowLayoutManager::Relayout() {
   }
 
   // Position docked windows as well as the window being dragged.
-  gfx::Rect work_area =
-      Shell::GetScreen()->GetDisplayNearestWindow(dock_container_).work_area();
+  gfx::Rect work_area = gfx::Screen::GetScreen()
+                            ->GetDisplayNearestWindow(dock_container_)
+                            .work_area();
   if (shelf_observer_)
     work_area.Subtract(shelf_observer_->shelf_bounds_in_screen());
   int available_room = CalculateWindowHeightsAndRemainingRoom(work_area,
@@ -1276,8 +1279,9 @@ void DockedWindowLayoutManager::FanOutChildren(
 void DockedWindowLayoutManager::UpdateDockBounds(
     DockedWindowLayoutManagerObserver::Reason reason) {
   int dock_inset = docked_width_ + (docked_width_ > 0 ? kMinDockGap : 0);
-  const gfx::Rect work_area =
-      Shell::GetScreen()->GetDisplayNearestWindow(dock_container_).work_area();
+  const gfx::Rect work_area = gfx::Screen::GetScreen()
+                                  ->GetDisplayNearestWindow(dock_container_)
+                                  .work_area();
   gfx::Rect bounds = gfx::Rect(
       alignment_ == DOCKED_ALIGNMENT_RIGHT && dock_inset > 0 ?
           dock_container_->bounds().right() - dock_inset: