hide internals of SkColorMatrix (so we can migrate to col-major)

Change-Id: If0eb6fb2efb6816b92ad7ca7d8caaace71397b7f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/209409
Commit-Queue: Ravi Mistry <rmistry@google.com>
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Auto-Submit: Mike Reed <reed@google.com>
diff --git a/gm/colorfilterimagefilter.cpp b/gm/colorfilterimagefilter.cpp
index 9cc2ccd..dca6486 100644
--- a/gm/colorfilterimagefilter.cpp
+++ b/gm/colorfilterimagefilter.cpp
@@ -178,7 +178,7 @@
     SkAutoCanvasRestore autoCanvasRestore(canvas, false);
     SkColorMatrix cm;
     cm.setSaturation(0.0f);
-    sk_sp<SkColorFilter> cf(SkColorFilters::MatrixRowMajor255(cm.fMat));
+    sk_sp<SkColorFilter> cf(SkColorFilters::Matrix(cm));
     SkPaint p;
     p.setImageFilter(SkColorFilterImageFilter::Make(std::move(cf), nullptr));
     canvas->saveLayer(nullptr, &p);