Add MD ink drop ripple to shelf app items

ui/views/controls/button/custom_button.h

Index: ui/views/controls/button/custom_button.h
diff --git a/ui/views/controls/button/custom_button.h b/ui/views/controls/button/custom_button.h
index 3dbec335993d42506198439916eda6767bfbad34..a73d5008cf67e90ce6790de0f9bca7660573736c 100644
--- a/ui/views/controls/button/custom_button.h
+++ b/ui/views/controls/button/custom_button.h
@@ -17,8 +17,6 @@
 
 namespace views {
 
-class InkDropDelegate;
-
 // A button with custom rendering. The base of ImageButton and LabelButton.
 // Note that this type of button is not focusable by default and will not be
 // part of the focus chain, unless in accessibility mode. Call
@@ -184,13 +182,8 @@ class VIEWS_EXPORT CustomButton : public Button, public gfx::AnimationDelegate {
 
   // True when a button click should trigger an animation action on
   // ink_drop_delegate().
-  // TODO(bruthig): Use an InkDropAction enum and drop the flag.
   bool has_ink_drop_action_on_click_;
 
-  // The animation action to trigger on ink_drop_delegate() when the button
-  // is clicked.
-  InkDropState ink_drop_action_on_click_;
-
   // When true, the ink drop ripple and hover will be hidden prior to showing
   // the context menu.
   bool hide_ink_drop_when_showing_context_menu_;