Add MD ink drop ripple to shelf app items

ash/shelf/app_list_button.h

Index: ash/shelf/app_list_button.h
diff --git a/ash/shelf/app_list_button.h b/ash/shelf/app_list_button.h
index 8983e37d97577fc02d7458d5e554bb803ffd6abc..df3d2a1eb310cf8ad5edd3ea5d44308e13ab4bf3 100644
--- a/ash/shelf/app_list_button.h
+++ b/ash/shelf/app_list_button.h
@@ -9,12 +9,14 @@
 #include "ui/views/controls/button/image_button.h"
 
 namespace ash {
+class InkDropButtonListener;
 class ShelfView;
 
 // Button used for the AppList icon on the shelf.
 class AppListButton : public views::ImageButton {
  public:
-  explicit AppListButton(ShelfView* shelf_view);
+  explicit AppListButton(InkDropButtonListener* listener,
+                         ShelfView* shelf_view);
   ~AppListButton() override;
 
   bool draw_background_as_active() { return draw_background_as_active_; }
@@ -27,6 +29,7 @@ class AppListButton : public views::ImageButton {
   bool OnMouseDragged(const ui::MouseEvent& event) override;
   void OnPaint(gfx::Canvas* canvas) override;
   void GetAccessibleState(ui::AXViewState* state) override;
+  void NotifyClick(const ui::Event& event) override;
 
   // ui::EventHandler overrides:
   void OnGestureEvent(ui::GestureEvent* event) override;
@@ -49,6 +52,7 @@ class AppListButton : public views::ImageButton {
   // the application list.
   bool draw_background_as_active_;
 
+  InkDropButtonListener* listener_;
   ShelfView* shelf_view_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListButton);