Touch ID platform authenticator in Chrome

Hey folks,

You can now test an early developer preview of the Touch ID WebAuthn
platform authenticator in Chrome Canary on macOS. (Here's a quick demo
<https://www.youtube.com/watch?v=JTJrvCcCFIc> of sign-in).

You will need:
- a Macbook Pro with the Touch Bar
- Chrome Canary <https://www.google.com/chrome/browser/canary.html> version
69.0.3468.0 or greater
- Touch ID enabled
<https://support.apple.com/kb/PH26216?viewlocale=en_US&locale=en_US> in the
OS

To use the authenticator, start Canary from the command line and enable its
feature flag: /Applications/Google\ Chrome\
Canary.app/Contents/MacOS/Google\ Chrome\ Canary
--enable-features=WebAuthenticationTouchId

Then go to a webauthn-enabled RP of your choice, for example Dropbox or
webauthndemo.appspot.com.

*Known issues:*

*- Users can't erase credentials on the Chrome-side yet.*
*- Touch ID only supports self attestation
<https://www.w3.org/TR/webauthn/#self-attestation>.*
- Touch ID is not supported in unsigned development builds.

​Feel free to file bugs at ​bugs.chromium.org
<https://bugs.chromium.org/p/chromium/issues/entry> against the component
"Blink>WebAuthentication". Send other queries to webauthn-team@google.com.

​Happy testing!​

​Kim, on behalf of Google's WebAuthN-team​

Kim Paulhamus |  Software Engineer |
 650.660.6213