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

Reverted because of picture/serialization failure

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1567063002

TBR=mtklein

Review URL: https://codereview.chromium.org/1567063002
diff --git a/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index d200e29..c7a37e7 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -1396,6 +1396,15 @@
 
     if (fUseMPD) {
         SkAutoTUnref<const SkPicture> picture(fRecorder.endRecording());
+
+        if (false) {
+            SkDynamicMemoryWStream wstream;
+            picture->serialize(&wstream);
+
+            SkAutoTDelete<SkStream> rstream(wstream.detachAsStream());
+            picture.reset(SkPicture::CreateFromStream(rstream));
+        }
+
         if (true) {
             if (true) {
                 SkImageInfo info;