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

src/effects/SkColorCubeFilter.cpp

Index: src/effects/SkColorCubeFilter.cpp
diff --git a/src/effects/SkColorCubeFilter.cpp b/src/effects/SkColorCubeFilter.cpp
index dd20a2701674e075bbeb0cfef67e6a1405c23cfd..9e2b08c91c783eebd5975cfd968288d197786624 100644
--- a/src/effects/SkColorCubeFilter.cpp
+++ b/src/effects/SkColorCubeFilter.cpp
@@ -240,7 +240,7 @@ private:
 ///////////////////////////////////////////////////////////////////////////////
 
 GrColorCubeEffect::GrColorCubeEffect(GrTexture* colorCube)
-    : fColorCubeTransform(kLocal_GrCoordSet, colorCube)
+    : fColorCubeTransform(kLocal_GrCoordSet, colorCube, GrTextureParams::kBilerp_FilterMode)
     , fColorCubeAccess(colorCube, "bgra", GrTextureParams::kBilerp_FilterMode) {
     this->initClassID<GrColorCubeEffect>();
     this->addCoordTransform(&fColorCubeTransform);