cc: Do not ignore layers without valid priorities during eviction.

cc/layers/picture_layer_impl.h

Index: cc/layers/picture_layer_impl.h
diff --git a/cc/layers/picture_layer_impl.h b/cc/layers/picture_layer_impl.h
index 024e31527e9c8413c7943d3f561451d459ba7b90..f93be8122fe222c5cdbd0a859eabe0d25bda2b1d 100644
--- a/cc/layers/picture_layer_impl.h
+++ b/cc/layers/picture_layer_impl.h
@@ -71,6 +71,7 @@ class CC_EXPORT PictureLayerImpl
    public:
     LayerEvictionTileIterator();
     LayerEvictionTileIterator(PictureLayerImpl* layer,
+                              const PictureLayerImpl* twin_layer,
                               TreePriority tree_priority);
     ~LayerEvictionTileIterator();
 
@@ -89,6 +90,8 @@ class CC_EXPORT PictureLayerImpl
 
     PictureLayerImpl* layer_;
     TreePriority tree_priority_;
+    bool use_tile_priority_rects_;
+    bool use_twin_tile_priority_rects_;
 
     PictureLayerTiling::EvictionCategory current_category_;
     PictureLayerTilingSet::TilingRangeType current_tiling_range_type_;