kByteLengthOffset is actually at the start of the object, so to avoid
confusion, put the accessor declarations in the same order as the
actual fields.

Change-Id: Ic92e597911235ccf126cf934151a0886e5d2a6f6
Reviewed-on: https://chromium-review.googlesource.com/725325Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48686}