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/GrStrokeRectOp.cpp b/src/gpu/ops/GrStrokeRectOp.cpp
index 83f6eee..db60858 100644
--- a/src/gpu/ops/GrStrokeRectOp.cpp
+++ b/src/gpu/ops/GrStrokeRectOp.cpp
@@ -640,7 +640,9 @@
 
     // We apply the viewmatrix to the rect points on the cpu.  However, if the pipeline uses
     // local coords then we won't be able to combine. TODO: Upload local coords as an attribute.
-    if (fHelper.usesLocalCoords() && !this->viewMatrix().cheapEqualTo(that->viewMatrix())) {
+    if (fHelper.usesLocalCoords() &&
+        !SkMatrixPriv::CheapEqual(this->viewMatrix(), that->viewMatrix()))
+    {
         return CombineResult::kCannotCombine;
     }