Revert[2] of "add backdrop option to SaveLayerRec"

src/core/SkRecordOpts.cpp

Index: src/core/SkRecordOpts.cpp
diff --git a/src/core/SkRecordOpts.cpp b/src/core/SkRecordOpts.cpp
index d1520adf561cdc0066e72bae863bc42a343e7dd4..2310e657d0321356083f9cc71c625fc04463a711 100644
--- a/src/core/SkRecordOpts.cpp
+++ b/src/core/SkRecordOpts.cpp
@@ -177,6 +177,11 @@ struct SaveLayerDrawRestoreNooper {
     typedef Pattern<Is<SaveLayer>, IsDraw, Is<Restore>> Match;
 
     bool onMatch(SkRecord* record, Match* match, int begin, int end) {
+        if (match->first<SaveLayer>()->backdrop) {
+            // can't throw away the layer if we have a backdrop
+            return false;
+        }
+
         // A SaveLayer's bounds field is just a hint, so we should be free to ignore it.
         SkPaint* layerPaint = match->first<SaveLayer>()->paint;
         if (nullptr == layerPaint) {