Mark AndroidWebViewVariationsEnableState histogram obsolete

This was added in 074de24df77eee54efbb6fc3646528b008bdb513. We stopped
logging it in 57e6c106954b12f71a6af72811eaa70ac81455b7.

BUG=871504

Change-Id: Id60307865b10192544480f3977f753bb93059b6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1601745
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Paul Miller <paulmiller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660206}
2 files changed