Add support for converting cc::FilterOperations into an SkImageFilter

cc/output/filter_operations.cc

Index: cc/output/filter_operations.cc
diff --git a/cc/output/filter_operations.cc b/cc/output/filter_operations.cc
index 43315279090f67861daff282214b6b70dd014029..ae0d16819b49c7265cb17ecc041efbd55cde3276 100644
--- a/cc/output/filter_operations.cc
+++ b/cc/output/filter_operations.cc
@@ -83,6 +83,7 @@ bool FilterOperations::HasFilterThatMovesPixels() const {
       case FilterOperation::BLUR:
       case FilterOperation::DROP_SHADOW:
       case FilterOperation::ZOOM:
+      case FilterOperation::REFERENCE:
         return true;
       default:
         break;
@@ -99,6 +100,7 @@ bool FilterOperations::HasFilterThatAffectsOpacity() const {
       case FilterOperation::BLUR:
       case FilterOperation::DROP_SHADOW:
       case FilterOperation::ZOOM:
+      case FilterOperation::REFERENCE:
         return true;
       case FilterOperation::COLOR_MATRIX: {
         const SkScalar* matrix = op.matrix();