Fix Fuchsia build errors (#4508)

flow/layers/physical_model_layer.cc

@@ -41,7 +41,8 @@ void PhysicalModelLayer::Preroll(PrerollContext* context,
 void PhysicalModelLayer::UpdateScene(SceneUpdateContext& context) {
   FXL_DCHECK(needs_system_composite());
 
-  SceneUpdateContext::Frame frame(context, rrect_, color_, elevation_);
+  SceneUpdateContext::Frame frame(context, shape_->getFrameRRect(), color_,
+                                  elevation_);
   for (auto& layer : layers()) {
     if (layer->needs_painting()) {
       frame.AddPaintedLayer(layer.get());

flow/layers/physical_model_layer.h

@@ -53,6 +53,7 @@ class PhysicalModelLayer : public ContainerLayer {
 // TODO(amirh): remove this once Scenic supports arbitrary shaped layers.
 class PhysicalLayerShape {
  public:
+  virtual ~PhysicalLayerShape() = default;
   virtual const SkRect& getBounds() const = 0;
   virtual SkPath getPath() const = 0;
   virtual void clipCanvas(SkCanvas& canvas) const = 0;