GitLab

Added Do... methods for each state in DoHandshakeLoop (similar to the
conventions that we typically use in our state machines).

DoVerifyProof and DoGetChannelID which could do async operation
return  QuicAsyncStatus.

In DoHandshakeLoop changed "for (;;) {" to be similar to other
do { ...} while loops of other state machines in chromium.

R=rch@chromium.org,agl@chromium.org

Review URL: https://codereview.chromium.org/588443002

Cr-Commit-Position: refs/heads/master@{#297316}