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 e40b5701e13286410170cac28dcf0f89a8237d62..0b7dc41d62289140e961f67d9867cb20a55db7a2 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -81,7 +81,9 @@ 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_);
@@ -353,6 +355,7 @@ 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
@@ -770,6 +773,15 @@ gfx::Vector2dF LayerImpl::ClampScrollToMaxScrollOffset() {
   return delta;
 }
 
+void LayerImpl::SetScrollBoundaryBehavior(
+    const 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;