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>
diff --git a/gm/imagefiltersbase.cpp b/gm/imagefiltersbase.cpp
index b30267a..440f6b2 100644
--- a/gm/imagefiltersbase.cpp
+++ b/gm/imagefiltersbase.cpp
@@ -194,7 +194,7 @@
             draw_bitmap,
         };
 
-        auto cf = SkColorFilter::MakeModeFilter(SK_ColorRED, SkXfermode::kSrcIn_Mode);
+        auto cf = SkColorFilter::MakeModeFilter(SK_ColorRED, SkBlendMode::kSrcIn);
         sk_sp<SkImageFilter> filters[] = {
             nullptr,
             IdentityImageFilter::Make(nullptr),
@@ -318,7 +318,7 @@
     ImageFiltersText_CF() : ImageFiltersTextBaseGM("color") {}
 
     void installFilter(SkPaint* paint) override {
-        paint->setColorFilter(SkColorFilter::MakeModeFilter(SK_ColorBLUE, SkXfermode::kSrcIn_Mode));
+        paint->setColorFilter(SkColorFilter::MakeModeFilter(SK_ColorBLUE, SkBlendMode::kSrcIn));
     }
 };
 DEF_GM( return new ImageFiltersText_CF; )