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 16bab888a6577fb5c57e8b95c6042647b69c4801..76ec509dbb7f67ff909a1185a4315d4a8f0b4af9 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -82,7 +82,9 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
       needs_push_properties_(false),
       scrollbars_hidden_(false),
       needs_show_scrollbars_(false),
-      raster_even_if_not_in_rsll_(false) {
+      raster_even_if_not_in_rsll_(false),
+      scroll_boundary_behavior_(
+          ScrollBoundaryBehavior::kScrollBoundaryBehaviorTypeAuto) {
   DCHECK_GT(layer_id_, 0);
 
   DCHECK(layer_tree_impl_);
@@ -354,6 +356,7 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   layer->SetBounds(bounds_);
   layer->SetScrollClipLayer(scroll_clip_layer_id_);
   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
@@ -771,6 +774,14 @@ gfx::Vector2dF LayerImpl::ClampScrollToMaxScrollOffset() {
   return delta;
 }
 
+void LayerImpl::SetScrollBoundaryBehavior(ScrollBoundaryBehavior behavior) {
+  if (scroll_boundary_behavior_ == behavior)
+    return;
+  scroll_boundary_behavior_ = behavior;
+  layer_tree_impl()->DidUpdateScrollState(id());
+  NoteLayerPropertyChanged();
+}
+
 void LayerImpl::SetNeedsPushProperties() {
   if (layer_tree_impl_ && !needs_push_properties_) {
     needs_push_properties_ = true;