I'm having difficulty saving a card to the server. I'm trying saving a new credit card using https://rsolomakhin.github.io/autofill/ but the SyncService returned here [1] is always NULL so the logic falls back to saving the card locally. Any hints on how to reproduce this?

[1] https://cs.chromium.org/chromium/src/components/autofill/core/browser/autofill_manager.cc?l=1092

Are you logged in? I don't know why you wouldn't have a sync service at all unless you weren't logged in or were using the command-line that disables sync.

In general, it's also worth being aware of go/testing-autofill-cc which lists various prerequisites and troubleshooting steps for upload, though most are downstream of sync actually working at all.

As usual, your docs are super useful and comprehensive. I was trying to upload a credit card in iOS! 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cff22de0743ef3de687e55c376b9733a0ff560a7

commit cff22de0743ef3de687e55c376b9733a0ff560a7
Author: mahmadi <mahmadi@chromium.org>
Date: Thu Jan 05 16:04:23 2017

Refactors cvc and expiration date validation in CC upload logic as well as unmask prompt.

BUG= 677519 

Signed-off-by: Mohamad Ahmadi <mahmadi@chromium.org>
Review-Url: https://codereview.chromium.org/2611863002
Cr-Commit-Position: refs/heads/master@{#441663}

[modify] https://crrev.com/cff22de0743ef3de687e55c376b9733a0ff560a7/components/autofill/core/browser/autofill_manager.cc
[modify] https://crrev.com/cff22de0743ef3de687e55c376b9733a0ff560a7/components/autofill/core/browser/autofill_manager_unittest.cc
[modify] https://crrev.com/cff22de0743ef3de687e55c376b9733a0ff560a7/components/autofill/core/browser/ui/card_unmask_prompt_controller_impl.cc
[modify] https://crrev.com/cff22de0743ef3de687e55c376b9733a0ff560a7/components/autofill/core/browser/validation.cc
[modify] https://crrev.com/cff22de0743ef3de687e55c376b9733a0ff560a7/components/autofill/core/browser/validation.h
[modify] https://crrev.com/cff22de0743ef3de687e55c376b9733a0ff560a7/components/autofill/core/browser/validation_unittest.cc