Revert[8] "replace SkXfermode obj with SkBlendMode enum in paints"

This reverts commit c245574ba3d0e2ade6c94b2812de3baa383bf4c4.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2396953002

TBR=

Review-Url: https://codereview.chromium.org/2396953002
diff --git a/gm/picture.cpp b/gm/picture.cpp
index 1ea8ada..72d4159 100644
--- a/gm/picture.cpp
+++ b/gm/picture.cpp
@@ -29,7 +29,7 @@
     canvas->drawPath(path, paint);
 
     paint.setColor(0x80FFFFFF);
-    paint.setXfermodeMode(SkXfermode::kPlus_Mode);
+    paint.setBlendMode(SkBlendMode::kPlus);
     canvas->drawRect(SkRect::MakeXYWH(25, 25, 50, 50), paint);
 
     return rec.finishRecordingAsPicture();