Remove unused field/methods

These have been replaced by duration on the base class.

Change-Id: Id87ecf09f4da6840280e3f5657453915a8d3c81b
Reviewed-on: https://skia-review.googlesource.com/99245
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
1 file changed