[not for review - epic CL] Adding Elastic+Momentum+Layered scrolling to views::ScrollView

ui/views/view.cc

Index: ui/views/view.cc
diff --git a/ui/views/view.cc b/ui/views/view.cc
index be3bbf5b7ed29370ae2f344bf04420ee029dbe93..658d02debc00f099d882ec07a5b80c0a1eaa258f 100644
--- a/ui/views/view.cc
+++ b/ui/views/view.cc
@@ -1355,6 +1355,10 @@ void View::ScrollRectToVisible(const gfx::Rect& rect) {
   }
 }
 
+ScrollView* View::EnclosingScrollView() {
+  return parent() ? parent()->EnclosingScrollView() : nullptr;
+}
+
 int View::GetPageScrollIncrement(ScrollView* scroll_view,
                                  bool is_horizontal, bool is_positive) {
   return 0;