Add MD ink drop ripple to app list button

ash/sysui/app_list_presenter_mus.h

 // Copyright 2016 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_SYSUI_APP_LIST_PRESENTER_MUS_H_
 #define ASH_SYSUI_APP_LIST_PRESENTER_MUS_H_
 
 #include "base/macros.h"
 #include "ui/app_list/presenter/app_list_presenter.h"
 #include "ui/app_list/presenter/app_list_presenter.mojom.h"
 
 namespace shell {
 class Connector;
 }
 
 namespace ash {
 
 // Mus+ash implementation of the AppListPresenter interface for mash, which
 // talks to the mojo app list service in chrome.
 class AppListPresenterMus : public app_list::AppListPresenter {
  public:
   explicit AppListPresenterMus(::shell::Connector* connector);
   ~AppListPresenterMus() override;
 
   // app_list::AppListPresenter:
   void Show(int64_t display_id) override;
   void Dismiss() override;
   void ToggleAppList(int64_t display_id) override;
+  bool IsVisible() const override;
   bool GetTargetVisibility() const override;
 
  private:
   // Connect to the mojo app list service in chrome if the connection hasn't
   // been established or has an error.
   bool ConnectIfNeeded();
 
   ::shell::Connector* connector_;
   app_list::mojom::AppListPresenterPtr presenter_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListPresenterMus);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSUI_APP_LIST_PRESENTER_MUS_H_