hide/remove obsolete/tricky SkMatrix methods

Change-Id: Iee399b929e8ca1a7326a326a643539d05e333d81
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/260818
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/src/gpu/effects/GrDistanceFieldGeoProc.cpp b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
index f828e50..d7c6cff 100644
--- a/src/gpu/effects/GrDistanceFieldGeoProc.cpp
+++ b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
@@ -463,7 +463,7 @@
                  const CoordTransformRange& transformRange) override {
         const GrDistanceFieldPathGeoProc& dfpgp = proc.cast<GrDistanceFieldPathGeoProc>();
 
-        if (dfpgp.matrix().hasPerspective() && !fMatrix.cheapEqualTo(dfpgp.matrix())) {
+        if (dfpgp.matrix().hasPerspective() && !SkMatrixPriv::CheapEqual(fMatrix, dfpgp.matrix())) {
             fMatrix = dfpgp.matrix();
             float matrix[3 * 3];
             GrGLSLGetMatrix<3>(matrix, fMatrix);