cc: Distinguish single texture mask from normal masks

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 5f777afcac3be247bdf526caa6fa875a3d3e0bf0..b98a36dcfcb6a37d89658c20a3a060226e5fcb36 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -420,6 +420,8 @@ void Layer::SetMaskLayer(Layer* mask_layer) {
     DCHECK(!inputs_.mask_layer->parent());
     inputs_.mask_layer->SetParent(this);
     inputs_.mask_layer->SetIsMask(true);
+    if (!inputs_.filters.IsEmpty())
+      inputs_.mask_layer->SetIsSingleTextureMask(true);
   }
   SetSubtreePropertyChanged();
   SetNeedsFullTreeSync();
@@ -430,6 +432,8 @@ void Layer::SetFilters(const FilterOperations& filters) {
   if (inputs_.filters == filters)
     return;
   inputs_.filters = filters;
+  if (inputs_.mask_layer)
+    inputs_.mask_layer->SetIsSingleTextureMask(true);
   SetSubtreePropertyChanged();
   SetNeedsCommit();
 }