remove xfermode from public api

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4020

CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Change-Id: I19cd056f2af778f10e8c6c2b7b2735593b43dbac
Reviewed-on: https://skia-review.googlesource.com/4020
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/bench/MergeBench.cpp b/bench/MergeBench.cpp
index 70b4744784..8b6004df1b 100644
--- a/bench/MergeBench.cpp
+++ b/bench/MergeBench.cpp
@@ -81,7 +81,7 @@ protected:
 private:
     sk_sp<SkImageFilter> mergeBitmaps() {
         return SkMergeImageFilter::Make(SkImageSource::Make(fCheckerboard),
-                                        SkImageSource::Make(fImage));
+                                        SkImageSource::Make(fImage), SkBlendMode::kSrcOver);
     }
 
     bool fIsSmall;