Add chrome://flags#enable-web-authentication-touch-id

This turns the existing WebAuthenticationTouchId feature into a
chrome://flags flag.

Bug: 678128
Change-Id: I8741f1d66409bdf636645c79cfb2145d679cb8d9
Reviewed-on: https://chromium-review.googlesource.com/1130699
Reviewed-by: Kim Paulhamus <kpaulhamus@chromium.org>
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#574001}
4 files changed