(See http://www.chromium.org/blink#launch-process for an overview)

Change description:
Enable RSA-PSS for TLS 1.2 in preparation for TLS 1.3.

Changes to API surface:
Chrome's ClientHello will include RSA-PSS values in the signature_algorithms extension and will accept RSA-PSS signatures for ServerKeyExchange.

Links:
Public standards discussion:
https://tools.ietf.org/html/draft-ietf-tls-tls13-15#section-4.2.2

Support in other browsers:
Internet Explorer:
Firefox: in progress as part of TLS 1.3 work
Safari:

(There's well-established consensus that TLS 1.3 will support RSA-PSS, so other browsers will likely support it once they get to 1.3.)

*Make sure to fill in any labels with a -?, including all OSes this change
affects. Feel free to leave other labels at the defaults.