Adding const to GetUncompressedSize

Change-Id: Ib538c60f5e1fa2e81432bc0992a482aced6eb7cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1897847


Auto-Submit: Sam Maier <smaier@chromium.org>
Reviewed-by: Adenilson Cavalcanti <cavalcantii@chromium.org>
Commit-Queue: Sam Maier <smaier@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#712161}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 60b63e2425bcb12ffd47527af414bd1ad8e7e631