Implement CSS: scroll-boundary-behavior

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 6e45fd3b02b62a6a08daa40a83f89129e0b55fc9..7e5439c5c7e844427c5ba2384d3374f254895ed2 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -80,7 +80,9 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
       scrollbars_hidden_(false),
       needs_show_scrollbars_(false),
       raster_even_if_not_drawn_(false),
-      has_transform_node_(false) {
+      has_transform_node_(false),
+      scroll_boundary_behavior_(
+          ScrollBoundaryBehavior::kScrollBoundaryBehaviorTypeAuto) {
   DCHECK_GT(layer_id_, 0);
 
   DCHECK(layer_tree_impl_);
@@ -337,6 +339,7 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   if (scrollable_)
     layer->SetScrollable(scroll_container_bounds_);
   layer->SetMutableProperties(mutable_properties_);
+  layer->SetScrollBoundaryBehavior(scroll_boundary_behavior_);
 
   // If the main thread commits multiple times before the impl thread actually
   // draws, then damage tracking will become incorrect if we simply clobber the
@@ -763,6 +766,14 @@ gfx::Vector2dF LayerImpl::ClampScrollToMaxScrollOffset() {
   return delta;
 }
 
+void LayerImpl::SetScrollBoundaryBehavior(
+    const ScrollBoundaryBehavior& behavior) {
+  if (scroll_boundary_behavior_ == behavior)
+    return;
+  scroll_boundary_behavior_ = behavior;
+  NoteLayerPropertyChanged();
+}
+
 void LayerImpl::SetNeedsPushProperties() {
   // There's no need to push layer properties on the active tree.
   if (!needs_push_properties_ && !layer_tree_impl()->IsActiveTree()) {