[Autofill Auth] Don't offer WebAuthn opt-in promo in incognito mode.

Ensuring that users don't get a WebAuthn opt-in promo while in incognito mode.
This also avoids a browser crash if a user attempts to downstream incognito.

Bug: 949269
Change-Id: I2b4af11a8bb1d8df115f0748d30d8785a99cfacc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1894291
Commit-Queue: Manas Verma <manasverma@google.com>
Reviewed-by: Jared Saul <jsaul@google.com>
Cr-Commit-Position: refs/heads/master@{#711890}

components/autofill/core/browser/payments/credit_card_access_manager.cc

@@ -231,7 +231,8 @@ void CreditCardAccessManager::OnDidGetUnmaskDetails(
       AutofillTickClock::NowTicks() - preflight_call_timestamp_);
 
   unmask_details_request_in_progress_ = false;
-  unmask_details_.offer_fido_opt_in = unmask_details.offer_fido_opt_in;
+  unmask_details_.offer_fido_opt_in = unmask_details.offer_fido_opt_in &&
+                                      !payments_client_->is_off_the_record();
   unmask_details_.unmask_auth_method = unmask_details.unmask_auth_method;
   unmask_details_.fido_request_options =
       std::move(unmask_details.fido_request_options);