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

cc/trees/property_tree_builder.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/property_tree_builder.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <set>
@@ skipping 640 matching lines @@
     data_for_children->property_trees->transform_tree
         .SetDeviceTransformScaleFactor(*data_from_ancestor.device_transform);
   } else {
     node->source_offset = source_offset;
     node->update_post_local_transform(layer->position(),
                                       TransformOrigin(layer));
   }
 
   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) {
     if (data_from_ancestor.affected_by_inner_viewport_bounds_delta) {
       node->affected_by_inner_viewport_bounds_delta_x =
           PositionConstraint(layer).is_fixed_to_right_edge();
       node->affected_by_inner_viewport_bounds_delta_y =
           PositionConstraint(layer).is_fixed_to_bottom_edge();
       if (node->affected_by_inner_viewport_bounds_delta_x ||
           node->affected_by_inner_viewport_bounds_delta_y) {
@@ skipping 458 matching lines @@
         data_for_children->property_trees->scroll_tree.Insert(node, parent_id);
     data_for_children->main_thread_scrolling_reasons =
         node.main_thread_scrolling_reasons;
     data_for_children->scroll_tree_parent_created_by_uninheritable_criteria =
         scroll_node_uninheritable_criteria;
     data_for_children->property_trees->scroll_id_to_index_map[layer->id()] =
         data_for_children->scroll_tree_parent;
 
     if (node.scrollable) {
       data_for_children->property_trees->scroll_tree.SetBaseScrollOffset(
-          layer->id(), layer->CurrentScrollOffset());
+          layer->id(), layer->CurrentScrollOffset(),
+          layer->CurrentOverscroll());
     }
   }
 
   layer->SetScrollTreeIndex(data_for_children->scroll_tree_parent);
 }
 
 template <typename LayerType>
 void SetBackfaceVisibilityTransform(LayerType* layer,
                                     bool created_transform_node) {
   const bool is_at_boundary_of_3d_rendering_context =
@@ skipping 324 matching lines @@
     color = SkColorSetA(color, 255);
   BuildPropertyTreesTopLevelInternal(
       root_layer, page_scale_layer, inner_viewport_scroll_layer,
       outer_viewport_scroll_layer, overscroll_elasticity_layer,
       elastic_overscroll, page_scale_factor, device_scale_factor, viewport,
       device_transform, property_trees, color);
   property_trees->ResetCachedData();
 }
 
 }  // namespace cc