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/ops/GrDefaultPathRenderer.cpp b/src/gpu/ops/GrDefaultPathRenderer.cpp
index 492bf65..ddbb809 100644
--- a/src/gpu/ops/GrDefaultPathRenderer.cpp
+++ b/src/gpu/ops/GrDefaultPathRenderer.cpp
@@ -464,7 +464,7 @@
             return CombineResult::kCannotCombine;
         }
 
-        if (!this->viewMatrix().cheapEqualTo(that->viewMatrix())) {
+        if (!SkMatrixPriv::CheapEqual(this->viewMatrix(), that->viewMatrix())) {
             return CombineResult::kCannotCombine;
         }