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/GrDefaultGeoProcFactory.cpp b/src/gpu/GrDefaultGeoProcFactory.cpp
index 1000bd1..03b3cdf 100644
--- a/src/gpu/GrDefaultGeoProcFactory.cpp
+++ b/src/gpu/GrDefaultGeoProcFactory.cpp
@@ -184,7 +184,9 @@
                      const CoordTransformRange& transformRange) override {
             const DefaultGeoProc& dgp = gp.cast<DefaultGeoProc>();
 
-            if (!dgp.viewMatrix().isIdentity() && !fViewMatrix.cheapEqualTo(dgp.viewMatrix())) {
+            if (!dgp.viewMatrix().isIdentity() &&
+                !SkMatrixPriv::CheapEqual(fViewMatrix, dgp.viewMatrix()))
+            {
                 fViewMatrix = dgp.viewMatrix();
                 float viewMatrix[3 * 3];
                 GrGLSLGetMatrix<3>(viewMatrix, fViewMatrix);