Implement a method to access the non-composited content root layer picture pile.

cc/picture_layer_impl.cc

Index: cc/picture_layer_impl.cc
diff --git a/cc/picture_layer_impl.cc b/cc/picture_layer_impl.cc
index 24f2b4791799e51fc078fe42310360bba4b55d2a..65f9640e28313f145960517a8a11f628398a038b 100644
--- a/cc/picture_layer_impl.cc
+++ b/cc/picture_layer_impl.cc
@@ -170,6 +170,10 @@ void PictureLayerImpl::didUpdateTransforms() {
   last_content_scale_y_ = contentsScaleY();
 }
 
+scoped_refptr<PicturePileImpl> PictureLayerImpl::GetPicturePileClone() const {
+  return pile_->CloneForDrawing();
+}
+
 void PictureLayerImpl::didUpdateBounds() {
   if (is_mask_)
     tilings_.Reset();