Implement RenewStreamForAuth for WebSockets

An implementation of HttpStream::RenewStreamForAuth() is needed for
connection reuse for authentication. Add an implementation to
WebSocketBasicHandshakeStream. Without the
"WebSocketHandshakeReuseConnection" feature enabled, the method returns
nullptr as before.

Add the WebSocketStreamCreateBasicAuthTest.SuccessfulConnectionReuse
test to verify that connection reuse is really working.

BUG=423609

Change-Id: I92d247c5204646f82894bce6c691f4711c571d0e
Reviewed-on: https://chromium-review.googlesource.com/1077876
Commit-Queue: Adam Rice <ricea@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564066}
3 files changed