cc: Distinguish single texture mask from normal masks

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 5f1ddf1b291ede8ce65a8367ccf47a654b0940ab..fb7059906e60c378e0ee60db405cfa7efcf0e79b 100644
--- a/cc/layers/picture_layer_impl.h
+++ b/cc/layers/picture_layer_impl.h
@@ -31,12 +31,15 @@ class CC_EXPORT PictureLayerImpl
  public:
   static std::unique_ptr<PictureLayerImpl> Create(LayerTreeImpl* tree_impl,
                                                   int id,
-                                                  bool is_mask) {
-    return base::WrapUnique(new PictureLayerImpl(tree_impl, id, is_mask));
+                                                  bool is_mask,
+                                                  bool is_single_texture_mask) {
+    return base::WrapUnique(
+        new PictureLayerImpl(tree_impl, id, is_mask, is_single_texture_mask));
   }
   ~PictureLayerImpl() override;
 
   bool is_mask() const { return is_mask_; }
+  bool is_single_texture_mask() const { return is_single_texture_mask_; }
 
   // LayerImpl overrides.
   const char* LayerTypeAsString() const override;
@@ -99,7 +102,10 @@ class CC_EXPORT PictureLayerImpl
   }
 
  protected:
-  PictureLayerImpl(LayerTreeImpl* tree_impl, int id, bool is_mask);
+  PictureLayerImpl(LayerTreeImpl* tree_impl,
+                   int id,
+                   bool is_mask,
+                   bool is_single_texture_mask);
   PictureLayerTiling* AddTiling(float contents_scale);
   void RemoveAllTilings();
   void AddTilingsForRasterScale();
@@ -144,6 +150,7 @@ class CC_EXPORT PictureLayerImpl
   bool was_screen_space_transform_animating_;
   bool only_used_low_res_last_append_quads_;
   const bool is_mask_;
+  const bool is_single_texture_mask_;
 
   bool nearest_neighbor_;
   bool is_directly_composited_image_;