Update the expiry date of the SR.BackgroundUseCaseTabCount histograms.

We're still using this data.

Bug: 948328
Change-Id: Ic53e5583d40a42c6891295d8b21e42a9cf678c1b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582220
Auto-Submit: S├ębastien Marchand <sebmarchand@chromium.org>
Commit-Queue: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654203}
1 file changed