Add field trial testing config for password manager onboarding

Bug: 983445
Change-Id: I0c246798453ed8b940ae65cd9ac32739a0b001d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1798354
Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Andrei Chulkov <achulkov@google.com>
Cr-Commit-Position: refs/heads/master@{#695987}
1 file changed