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

ash/shelf/shelf.h

 // 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.
 
 #ifndef ASH_SHELF_SHELF_H_
 #define ASH_SHELF_SHELF_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 38 matching lines @@
 
 // Controller for shelf state. All access to state (visibility, auto-hide, etc.)
 // should occur via this class.
 class ASH_EXPORT Shelf {
  public:
   static const char kNativeViewName[];
 
   Shelf(ShelfModel* model,
         WmShelf* wm_shelf,
         ShelfWidget* widget);
-  virtual ~Shelf();
+  ~Shelf();
 
   // Return the shelf for the primary display. NULL if no user is logged in yet.
   // Useful for tests. For production code use ForWindow() because the user may
   // have multiple displays.
   static Shelf* ForPrimaryDisplay();
 
   // Return the shelf for the display that |window| is currently on, or a shelf
   // on primary display if the shelf per display feature is disabled. NULL if no
   // user is logged in yet.
   static Shelf* ForWindow(const aura::Window* window);
@@ skipping 75 matching lines @@
     return shelf_widget_->shelf_layout_manager();
   }
 
   // Returns rectangle bounding all visible shelf items. Used screen coordinate
   // system.
   gfx::Rect GetVisibleItemsBoundsInScreen() const;
 
   // Returns ApplicationDragAndDropHost for this shelf.
   app_list::ApplicationDragAndDropHost* GetDragAndDropHostForAppList();
 
+  // Updates the background for the shelf items.
+  void UpdateShelfItemBackground(int alpha);
+
   ShelfLockingManager* shelf_locking_manager_for_testing() {
     return &shelf_locking_manager_;
   }
 
   ShelfView* shelf_view_for_testing() { return shelf_view_; }
 
  private:
   friend class test::ShelfTestAPI;
 
   // The shelf controller. Owned by the root window controller.
   WmShelf* wm_shelf_;
   ShelfWidget* shelf_widget_;
   ShelfView* shelf_view_;
   ShelfLockingManager shelf_locking_manager_;
 
   ShelfAlignment alignment_ = SHELF_ALIGNMENT_BOTTOM;
   ShelfAutoHideBehavior auto_hide_behavior_ = SHELF_AUTO_HIDE_BEHAVIOR_NEVER;
 
   DISALLOW_COPY_AND_ASSIGN(Shelf);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_SHELF_H_