Revert of Replaced BackgroundAnimator with ShelfBackgroundAnimator.

ash/shelf/shelf.cc

Index: ash/shelf/shelf.cc
diff --git a/ash/shelf/shelf.cc b/ash/shelf/shelf.cc
index fa88c8c65e66e337c136c1f5b731a4bc83cf2dff..a557586399a669219bb74b1273aa92156dccbfd3 100644
--- a/ash/shelf/shelf.cc
+++ b/ash/shelf/shelf.cc
@@ -41,15 +41,13 @@
 
 Shelf::Shelf(ShelfModel* shelf_model,
              WmShelf* wm_shelf,
-             ShelfWidget* shelf_widget,
-             ShelfBackgroundAnimator* background_animator)
+             ShelfWidget* shelf_widget)
     : wm_shelf_(wm_shelf),
       shelf_widget_(shelf_widget),
       shelf_view_(new ShelfView(shelf_model,
                                 WmShell::Get()->shelf_delegate(),
                                 wm_shelf,
-                                this,
-                                background_animator)),
+                                this)),
       shelf_locking_manager_(wm_shelf) {
   DCHECK(wm_shelf_);
   shelf_view_->Init();