Support tls-server-end-point channel bindings for HTTP authentication.

net/http/proxy_client_socket.cc

Index: net/http/proxy_client_socket.cc
diff --git a/net/http/proxy_client_socket.cc b/net/http/proxy_client_socket.cc
index 3a7947c02486815bc6782ec9f8db5b2f0da3cf6f..f9373e0336a776f63f520755014c1855d0e4f616 100644
--- a/net/http/proxy_client_socket.cc
+++ b/net/http/proxy_client_socket.cc
@@ -57,8 +57,7 @@ void ProxyClientSocket::BuildTunnelRequest(
 int ProxyClientSocket::HandleProxyAuthChallenge(HttpAuthController* auth,
                                                 HttpResponseInfo* response,
                                                 const BoundNetLog& net_log) {
-  DCHECK(response->headers.get());
-  int rv = auth->HandleAuthChallenge(response->headers, false, true, net_log);
+  int rv = auth->HandleAuthChallenge(*response, false, true, net_log);
   response->auth_challenge = auth->auth_info();
   if (rv == OK)
     return ERR_PROXY_AUTH_REQUESTED;