[canvaskit] Refactor with getTotalMatrix

Follow up from https://skia-review.googlesource.com/c/skia/+/174843

Bug: skia:
Change-Id: I3b99d8550ecdf8085e11b6fbfbb304c857061149
Reviewed-on: https://skia-review.googlesource.com/c/175583
Reviewed-by: Florin Malita <fmalita@chromium.org>
4 files changed