share code around animating the rotating cube

Change-Id: I90e0918b1ce6df7f54fae67916754289eb9a263b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/272638
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed