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

cc/trees/property_tree_builder.cc

Index: cc/trees/property_tree_builder.cc
diff --git a/cc/trees/property_tree_builder.cc b/cc/trees/property_tree_builder.cc
index 8df219660cf8daa71772fda69835ec3668245c93..9760b329123a38e609a04ad471990be41b267f5a 100644
--- a/cc/trees/property_tree_builder.cc
+++ b/cc/trees/property_tree_builder.cc
@@ -653,10 +653,11 @@ bool AddTransformNodeIfNeeded(
 
   if (is_overscroll_elasticity_layer) {
     DCHECK(!is_scrollable);
-    node->scroll_offset =
+    node->scroll_offset_with_overscroll =
         gfx::ScrollOffset(data_from_ancestor.elastic_overscroll);
   } else if (!ScrollParent(layer)) {
-    node->scroll_offset = layer->CurrentScrollOffset();
+    node->scroll_offset_with_overscroll =
+        layer->CurrentScrollOffset() + layer->CurrentOverscroll();
   }
 
   if (is_fixed) {
@@ -1118,7 +1119,8 @@ void AddScrollNodeIfNeeded(
 
     if (node.scrollable) {
       data_for_children->property_trees->scroll_tree.SetBaseScrollOffset(
-          layer->id(), layer->CurrentScrollOffset());
+          layer->id(), layer->CurrentScrollOffset(),
+          layer->CurrentOverscroll());
     }
   }