Add ink drop masking to TrayBackgroundView

ash/common/system/tray/tray_background_view.h

 // 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.
 
 #ifndef ASH_COMMON_SYSTEM_TRAY_TRAY_BACKGROUND_VIEW_H_
 #define ASH_COMMON_SYSTEM_TRAY_TRAY_BACKGROUND_VIEW_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 121 matching lines @@
   void UpdateBubbleViewArrow(views::TrayBubbleView* bubble_view);
 
   // ShelfBackgroundAnimatorObserver:
   void UpdateShelfItemBackground(int alpha) override;
 
   // Updates the visibility of this tray's separator.
   void SetSeparatorVisibility(bool is_show);
 
  protected:
   // ActionableView:
+  std::unique_ptr<views::InkDropMask> CreateInkDropMask() const override;
   bool ShouldEnterPushedState(const ui::Event& event) override;
   bool PerformAction(const ui::Event& event) override;
   void HandlePerformActionResult(bool action_performed,
                                  const ui::Event& event) override;
   gfx::Rect GetFocusBounds() override;
 
  private:
   class TrayWidgetObserver;
 
   // ui::ImplicitAnimationObserver:
@@ skipping 27 matching lines @@
 
   std::unique_ptr<TrayWidgetObserver> widget_observer_;
   std::unique_ptr<TrayEventFilter> tray_event_filter_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayBackgroundView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_TRAY_BACKGROUND_VIEW_H_