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 8af3d1e4882ceaef8a3df332948e784c3b0fe990..63138dddb26eac2211a1f24c6c727255a64b99ae 100644
--- a/ash/shelf/shelf_view.h
+++ b/ash/shelf/shelf_view.h
@@ -11,6 +11,7 @@
 #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"
@@ -44,6 +45,7 @@ class OverflowBubble;
 class OverflowButton;
 class ScopedTargetRootWindow;
 class Shelf;
+class ShelfBackgroundAnimator;
 class ShelfButton;
 class ShelfDelegate;
 class ShelfIconObserver;
@@ -61,6 +63,7 @@ extern const int SHELF_ALIGNMENT_UMA_ENUM_VALUE_RIGHT;
 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,
@@ -71,7 +74,8 @@ class ASH_EXPORT ShelfView : public views::View,
   ShelfView(ShelfModel* model,
             ShelfDelegate* delegate,
             WmShelf* wm_shelf,
-            Shelf* shelf);
+            Shelf* shelf,
+            ShelfBackgroundAnimator* background_animator);
   ~ShelfView() override;
 
   Shelf* shelf() const { return shelf_; }
@@ -283,6 +287,9 @@ class ASH_EXPORT ShelfView : public views::View,
   // 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;
@@ -468,6 +475,9 @@ class ASH_EXPORT ShelfView : public views::View,
   // 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);
 };