Reland of "Apply Shelf/Dock opacity animations for the Material Design style."

ash/shelf/shelf.cc

 // Copyright 2013 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.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "ash/aura/wm_window_aura.h"
@@ skipping 198 matching lines @@
 }
 
 gfx::Rect Shelf::GetVisibleItemsBoundsInScreen() const {
   return shelf_view_->GetVisibleItemsBoundsInScreen();
 }
 
 app_list::ApplicationDragAndDropHost* Shelf::GetDragAndDropHostForAppList() {
   return shelf_view_;
 }
 
+void Shelf::UpdateShelfItemBackground(int alpha) {
+  shelf_view_->UpdateShelfItemBackground(alpha);
+}
+
 }  // namespace ash