Add ink drop ripple to overview mode button

ui/views/animation/ink_drop_host_view.h

Index: ui/views/animation/ink_drop_host_view.h
diff --git a/ui/views/animation/ink_drop_host_view.h b/ui/views/animation/ink_drop_host_view.h
index c61c1f091d9815c231e0f262cb4475e314ac162b..3419e531a653e71933f4d221bb4597f2dea17923 100644
--- a/ui/views/animation/ink_drop_host_view.h
+++ b/ui/views/animation/ink_drop_host_view.h
@@ -109,6 +109,8 @@ class VIEWS_EXPORT InkDropHostView : public View, public InkDropHost {
   // of CreateInkDrop() delegates to this function.
   std::unique_ptr<InkDropImpl> CreateDefaultInkDropImpl();
 
+  InkDropMode ink_drop_mode() const { return ink_drop_mode_; }
+
  private:
   class InkDropGestureHandler;
   friend class InkDropGestureHandler;