Use threshold of 1 texture coord value per pixel w/ nearest neighbor.

src/effects/SkDisplacementMapEffect.cpp

Index: src/effects/SkDisplacementMapEffect.cpp
diff --git a/src/effects/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index f13a3494fd25936c3498a7f25d6e6235546c116b..f10af7079bdd2a50ccb5b4c340f5c736c385c8c9 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -454,9 +454,10 @@ GrDisplacementMapEffect::GrDisplacementMapEffect(
                              GrTexture* displacement,
                              const SkMatrix& offsetMatrix,
                              GrTexture* color)
-    : fDisplacementTransform(kLocal_GrCoordSet, offsetMatrix, displacement)
+    : fDisplacementTransform(kLocal_GrCoordSet, offsetMatrix, displacement,
+                             GrTextureParams::kNone_FilterMode)
     , fDisplacementAccess(displacement)
-    , fColorTransform(kLocal_GrCoordSet, color)
+    , fColorTransform(kLocal_GrCoordSet, color, GrTextureParams::kNone_FilterMode)
     , fColorAccess(color)
     , fXChannelSelector(xChannelSelector)
     , fYChannelSelector(yChannelSelector)