[Autofill] Parameterizes flag for mobile label experiment.

Bug: 957426
Change-Id: I15acd48fab75d670ff74c8855697db201119d5c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1623126
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#663046}
4 files changed