By comparing key type with KT_DEFAULT we remove the implicit assumption that the default is RSA. Removing the assumptions about what the default is is necessary for a follow-up CL that will change the default. BUG=webrtc:5795, webrtc:5707 R=hta@webrtc.org, magjed@webrtc.org, tommi@webrtc.org TBR=tkchin@webrtc.org Review URL: https://codereview.webrtc.org/1965313002 . Cr-Commit-Position: refs/heads/master@{#12722}