replace SkXfermode obj with SkBlendMode enum in paints

BUG=skia:5814

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2714

Change-Id: I4fb489ba6b3f77b458f7e4a99f79c7ad10859135
Reviewed-on: https://skia-review.googlesource.com/2714
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/src/effects/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index 4f6386d..6c779b7 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -343,7 +343,7 @@
                                           offsetMatrix,
                                           colorTexture.get(),
                                           SkISize::Make(color->width(), color->height())));
-        paint.setPorterDuffXPFactory(SkXfermode::kSrc_Mode);
+        paint.setPorterDuffXPFactory(SkBlendMode::kSrc);
         SkMatrix matrix;
         matrix.setTranslate(-SkIntToScalar(colorBounds.x()), -SkIntToScalar(colorBounds.y()));