The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/af6a20e4e7edcd9b81e11a7d8653c1fd279484be

commit af6a20e4e7edcd9b81e11a7d8653c1fd279484be
Author: Jun Choi <hongjunchoi@chromium.org>
Date: Thu Aug 02 01:56:13 2018

Save previously used transport type for WebAuthn UI

Use Chromium pref as a persistant key-value storage to save previously
used transport type. This will enable us to skip "Welcome" dialog if we
know that the user has already used certain transport type before.

Bug:  868212 
Change-Id: Iff732f2d990291cfe1465107fc01d08b3cf3e019
Reviewed-on: https://chromium-review.googlesource.com/1152559
Commit-Queue: Jun Choi <hongjunchoi@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Kim Paulhamus <kpaulhamus@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580028}
[modify] https://crrev.com/af6a20e4e7edcd9b81e11a7d8653c1fd279484be/chrome/browser/webauthn/chrome_authenticator_request_delegate.cc
[modify] https://crrev.com/af6a20e4e7edcd9b81e11a7d8653c1fd279484be/chrome/browser/webauthn/chrome_authenticator_request_delegate.h
[modify] https://crrev.com/af6a20e4e7edcd9b81e11a7d8653c1fd279484be/chrome/browser/webauthn/chrome_authenticator_request_delegate_unittest.cc
[modify] https://crrev.com/af6a20e4e7edcd9b81e11a7d8653c1fd279484be/content/public/browser/authenticator_request_client_delegate.cc
[modify] https://crrev.com/af6a20e4e7edcd9b81e11a7d8653c1fd279484be/content/public/browser/authenticator_request_client_delegate.h
[modify] https://crrev.com/af6a20e4e7edcd9b81e11a7d8653c1fd279484be/device/fido/BUILD.gn
[add] https://crrev.com/af6a20e4e7edcd9b81e11a7d8653c1fd279484be/device/fido/fido_transport_protocol.cc
[modify] https://crrev.com/af6a20e4e7edcd9b81e11a7d8653c1fd279484be/device/fido/fido_transport_protocol.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cc52cb42bf1edb96bba182bf328e8c131f295e49

commit cc52cb42bf1edb96bba182bf328e8c131f295e49
Author: Jun Choi <hongjunchoi@chromium.org>
Date: Tue Aug 21 05:27:40 2018

Disable auto transport selection on MakeCredential

In current implementation, we auto-select transport type to previously
used transport type. Disable this feature for MakeCredential request.

Bug:  868212 
Change-Id: I4b0c3e642df1eaffa8f76956223a6a7f9b66a21b
Reviewed-on: https://chromium-review.googlesource.com/1182101
Commit-Queue: Jun Choi <hongjunchoi@chromium.org>
Reviewed-by: Balazs Engedy <engedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584658}
[modify] https://crrev.com/cc52cb42bf1edb96bba182bf328e8c131f295e49/chrome/browser/webauthn/authenticator_request_dialog_model.cc
[modify] https://crrev.com/cc52cb42bf1edb96bba182bf328e8c131f295e49/chrome/browser/webauthn/authenticator_request_dialog_model_unittest.cc