Replaced BackgroundAnimator with ShelfBackgroundAnimator.

ash/shelf/shelf_view.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/shelf/shelf_view.h"
 
 #include <algorithm>
 #include <memory>
 
 #include "ash/aura/wm_window_aura.h"
@@ skipping 775 matching lines @@
     FinalizeRipOffDrag(false);
     drag_pointer_ = NONE;
     AnimateToIdealBounds();
   }
   // If the drag pointer is NONE, no drag operation is going on and the
   // drag_view can be released.
   if (drag_pointer_ == NONE)
     drag_view_ = nullptr;
 }
 
+void ShelfView::UpdateShelfItemBackground(int alpha) {
+  GetAppListButton()->SetBackgroundAlpha(alpha);
+  overflow_button_->SetBackgroundAlpha(alpha);
+}
+
 void ShelfView::LayoutToIdealBounds() {
   if (bounds_animator_->IsAnimating()) {
     AnimateToIdealBounds();
     return;
   }
 
   IdealBounds ideal_bounds;
   CalculateIdealBounds(&ideal_bounds);
   views::ViewModelUtils::SetViewBoundsToIdealBounds(*view_model_);
   overflow_button_->SetBoundsRect(ideal_bounds.overflow_bounds);
@@ skipping 1101 matching lines @@
 
 int ShelfView::CalculateShelfDistance(const gfx::Point& coordinate) const {
   const gfx::Rect bounds = GetBoundsInScreen();
   int distance = shelf_->SelectValueForShelfAlignment(
       bounds.y() - coordinate.y(), coordinate.x() - bounds.right(),
       bounds.x() - coordinate.x());
   return distance > 0 ? distance : 0;
 }
 
 }  // namespace ash