Treat QUIC proxy as a valid HTTP proxy.

QUIC Proxy servers are valid HTTP proxies and should be treated
as such. This is required for using Chrome with a QUIC-based data
reduction proxy.

BUG=343579

Review URL: https://codereview.chromium.org/880483004

Cr-Commit-Position: refs/heads/master@{#314879}
diff --git a/net/http/http_network_transaction.cc b/net/http/http_network_transaction.cc
index 8f33e20..69a3aa5 100644
--- a/net/http/http_network_transaction.cc
+++ b/net/http/http_network_transaction.cc
@@ -571,7 +571,8 @@
 }
 
 bool HttpNetworkTransaction::UsingHttpProxyWithoutTunnel() const {
-  return (proxy_info_.is_http() || proxy_info_.is_https()) &&
+  return (proxy_info_.is_http() || proxy_info_.is_https() ||
+          proxy_info_.is_quic()) &&
          !(request_->url.SchemeIs("https") || request_->url.SchemeIsWSOrWSS());
 }