Revert of Replaced BackgroundAnimator with ShelfBackgroundAnimator.

ash/shelf/shelf_widget.h

Index: ash/shelf/shelf_widget.h
diff --git a/ash/shelf/shelf_widget.h b/ash/shelf/shelf_widget.h
index ccd85d7eef93cb12255fa811f722ad917f5f1293..af6de3defeb81d3fd61485a5edb71f769c09d5db 100644
--- a/ash/shelf/shelf_widget.h
+++ b/ash/shelf/shelf_widget.h
@@ -8,8 +8,8 @@
 #include <memory>
 
 #include "ash/ash_export.h"
-#include "ash/common/shelf/shelf_background_animator.h"
 #include "ash/common/shelf/shelf_types.h"
+#include "ash/common/wm/background_animator.h"
 #include "ash/shelf/shelf_layout_manager_observer.h"
 #include "base/macros.h"
 #include "ui/views/widget/widget.h"
@@ -59,7 +59,7 @@
   Shelf* shelf() const { return shelf_.get(); }
   StatusAreaWidget* status_area_widget() const { return status_area_widget_; }
 
-  void CreateShelf();
+  void CreateShelf(WmShelfAura* wm_shelf_aura);
   void PostCreateShelf();
 
   // Set visibility of the shelf.
@@ -104,8 +104,6 @@
   void OnMouseEvent(ui::MouseEvent* event) override;
   void OnGestureEvent(ui::GestureEvent* event) override;
 
-  WmShelfAura* wm_shelf_aura_;
-
   // Owned by the shelf container's aura::Window.
   ShelfLayoutManager* shelf_layout_manager_;
   std::unique_ptr<Shelf> shelf_;
@@ -114,7 +112,7 @@
   // |delegate_view_| is the contents view of this widget and is cleaned up
   // during CloseChildWindows of the associated RootWindowController.
   DelegateView* delegate_view_;
-  ShelfBackgroundAnimator background_animator_;
+  BackgroundAnimator background_animator_;
   bool activating_as_fallback_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfWidget);