Remove non-MD code from TrayBackgroundView

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 995e4d5c459f3f55a4531567ae266628b46f48cd..1b6843aabfb6d9955f5e9dbf639e7a3428f98c6b 100644
--- a/ui/views/animation/ink_drop_host_view.h
+++ b/ui/views/animation/ink_drop_host_view.h
@@ -122,8 +122,6 @@ 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;