Backport r17761 from the trunk to the 172 branch....

net/http/http_network_transaction.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/http/http_network_transaction.h"
 
 #include "base/scoped_ptr.h"
 #include "base/compiler_specific.h"
 #include "base/field_trial.h"
 #include "base/string_util.h"
@@ skipping 328 matching lines @@
 
   request_headers_ += request_->extra_headers;
   request_headers_ += "\r\n";
 }
 
 // The HTTP CONNECT method for establishing a tunnel connection is documented
 // in draft-luotonen-web-proxy-tunneling-01.txt and RFC 2817, Sections 5.2 and
 // 5.3.
 void HttpNetworkTransaction::BuildTunnelRequest() {
   // RFC 2616 Section 9 says the Host request-header field MUST accompany all
-  // HTTP/1.1 requests.
+  // HTTP/1.1 requests.  Add "Proxy-Connection: keep-alive" for compat with
+  // HTTP/1.0 proxies such as Squid (required for NTLM authentication).
   request_headers_ = StringPrintf("CONNECT %s:%d HTTP/1.1\r\n",
       request_->url.host().c_str(), request_->url.EffectiveIntPort());
   request_headers_ += "Host: " + request_->url.host();
   if (request_->url.has_port())
     request_headers_ += ":" + request_->url.port();
-  request_headers_ += "\r\n";
+  request_headers_ += "\r\nProxy-Connection: keep-alive\r\n";
 
   if (!request_->user_agent.empty())
     request_headers_ += "User-Agent: " + request_->user_agent + "\r\n";
 
   ApplyAuth();
 
   request_headers_ += "\r\n";
 }
 
 void HttpNetworkTransaction::DoCallback(int rv) {
@@ skipping 1175 matching lines @@
   if (target == HttpAuth::AUTH_PROXY) {
     auth_info->host = ASCIIToWide(proxy_info_.proxy_server().host_and_port());
   } else {
     DCHECK(target == HttpAuth::AUTH_SERVER);
     auth_info->host = ASCIIToWide(request_->url.host());
   }
   response_.auth_challenge = auth_info;
 }
 
 }  // namespace net