tls: Make xml values all oneof

Bug: 1026860
Change-Id: I4f32de69ce4238e1888121382234cf3ba40c9fa3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/1986324
Commit-Queue: Allen Li <ayatane@chromium.org>
Tested-by: Allen Li <ayatane@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
3 files changed