clean up now that min_stride == 1

Change-Id: I1c285e818c3119bc5917dee6d7fbe4c0c62ff6d7
Reviewed-on: https://skia-review.googlesource.com/18153
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
4 files changed