Implemented mid-level Negotiate protocol for Posix.

net/http/http_network_transaction_unittest.cc

Index: net/http/http_network_transaction_unittest.cc
diff --git a/net/http/http_network_transaction_unittest.cc b/net/http/http_network_transaction_unittest.cc
index b4278146878049b73cd3becabe529959f5d366f0..97bb61ec6530b477e0eaaeb22454ef99eddebdf2 100644
--- a/net/http/http_network_transaction_unittest.cc
+++ b/net/http/http_network_transaction_unittest.cc
@@ -1808,8 +1808,9 @@ TEST_F(HttpNetworkTransactionTest, NTLMAuth1) {
 
   MockRead data_reads1[] = {
     MockRead("HTTP/1.1 401 Access Denied\r\n"),
-    // Negotiate and NTLM are often requested together.  We only support NTLM.
-    MockRead("WWW-Authenticate: Negotiate\r\n"),
+    // Negotiate and NTLM are often requested together.  However, we only want to test
+    // NTLM while Negotiate is preferred over NTLM, so we skip that header.
+    // MockRead("WWW-Authenticate: Negotiate\r\n"),
     MockRead("WWW-Authenticate: NTLM\r\n"),
     MockRead("Connection: close\r\n"),
     MockRead("Content-Length: 42\r\n"),
@@ -1931,8 +1932,9 @@ TEST_F(HttpNetworkTransactionTest, NTLMAuth2) {
 
   MockRead data_reads1[] = {
     MockRead("HTTP/1.1 401 Access Denied\r\n"),
-    // Negotiate and NTLM are often requested together.  We only support NTLM.
-    MockRead("WWW-Authenticate: Negotiate\r\n"),
+    // Negotiate and NTLM are often requested together.  However, we only want to test
+    // NTLM while Negotiate is preferred over NTLM, so we skip that header.
+    // MockRead("WWW-Authenticate: Negotiate\r\n"),
     MockRead("WWW-Authenticate: NTLM\r\n"),
     MockRead("Connection: close\r\n"),
     MockRead("Content-Length: 42\r\n"),
@@ -1981,7 +1983,7 @@ TEST_F(HttpNetworkTransactionTest, NTLMAuth2) {
 
     // Wrong password.
     MockRead("HTTP/1.1 401 Access Denied\r\n"),
-    MockRead("WWW-Authenticate: Negotiate\r\n"),
+    // MockRead("WWW-Authenticate: Negotiate\r\n"),
     MockRead("WWW-Authenticate: NTLM\r\n"),
     MockRead("Connection: close\r\n"),
     MockRead("Content-Length: 42\r\n"),