Revert of Replaced BackgroundAnimator with ShelfBackgroundAnimator.

ash/shelf/shelf_view.h

Index: ash/shelf/shelf_view.h
diff --git a/ash/shelf/shelf_view.h b/ash/shelf/shelf_view.h
index 63138dddb26eac2211a1f24c6c727255a64b99ae..8af3d1e4882ceaef8a3df332948e784c3b0fe990 100644
--- a/ash/shelf/shelf_view.h
+++ b/ash/shelf/shelf_view.h
@@ -11,7 +11,6 @@
 #include <vector>
 
 #include "ash/common/shelf/ink_drop_button_listener.h"
-#include "ash/common/shelf/shelf_background_animator_observer.h"
 #include "ash/common/shelf/shelf_button_pressed_metric_tracker.h"
 #include "ash/common/shelf/shelf_item_delegate.h"
 #include "ash/common/shelf/shelf_model_observer.h"
@@ -45,7 +44,6 @@
 class OverflowButton;
 class ScopedTargetRootWindow;
 class Shelf;
-class ShelfBackgroundAnimator;
 class ShelfButton;
 class ShelfDelegate;
 class ShelfIconObserver;
@@ -63,7 +61,6 @@
 extern const int SHELF_ALIGNMENT_UMA_ENUM_VALUE_COUNT;
 
 class ASH_EXPORT ShelfView : public views::View,
-                             public ShelfBackgroundAnimatorObserver,
                              public ShelfModelObserver,
                              public InkDropButtonListener,
                              public views::ContextMenuController,
@@ -74,8 +71,7 @@
   ShelfView(ShelfModel* model,
             ShelfDelegate* delegate,
             WmShelf* wm_shelf,
-            Shelf* shelf,
-            ShelfBackgroundAnimator* background_animator);
+            Shelf* shelf);
   ~ShelfView() override;
 
   Shelf* shelf() const { return shelf_; }
@@ -287,9 +283,6 @@
   // Overridden from ui::EventHandler:
   void OnGestureEvent(ui::GestureEvent* event) override;
 
-  // ShelfBackgroundAnimatorObserver:
-  void UpdateShelfItemBackground(int alpha) override;
-
   // Overridden from ShelfModelObserver:
   void ShelfItemAdded(int model_index) override;
   void ShelfItemRemoved(int model_index, ShelfID id) override;
@@ -475,9 +468,6 @@
   // Tracks UMA metrics based on shelf button press actions.
   ShelfButtonPressedMetricTracker shelf_button_pressed_metric_tracker_;
 
-  // The background animator to observe. Can be null.
-  ShelfBackgroundAnimator* background_animator_;
-
   DISALLOW_COPY_AND_ASSIGN(ShelfView);
 };