Modernize AuthenticationService use of base::Value API

Change AuthenticationService to use the new base::Value API. This
is a purely mechanical change to remove use of deprecated APIs.

Bug: none
Change-Id: I17ae041cab9823ea7562b29faca085629a3766d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1569715
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: David Roger <droger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653158}
1 file changed