Set Token-Binding HTTP header

Adds a new method to SSLClientSocket to get the Token Binding from an SSL
connection where Token Binding was negotiated, and uses that to add the
Set-Token-Binding HTTP header (only when Token Binding was negotiated).

BUG=467312

Review URL: https://codereview.chromium.org/1378613004

Cr-Original-Commit-Position: refs/heads/master@{#371347}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: b7441ef2effe86324798710a82d8a006f5eb1395
4 files changed