Use AuthCredentials throughout the network stack instead of username/password.

net/http/http_transaction_unittest.cc

Index: net/http/http_transaction_unittest.cc
diff --git a/net/http/http_transaction_unittest.cc b/net/http/http_transaction_unittest.cc
index 40ea6f00c55c89a051cfcd33b1c9854c4d85f908..ff86bc1109b34ab733cd49a9d926ce398ee77c01 100644
--- a/net/http/http_transaction_unittest.cc
+++ b/net/http/http_transaction_unittest.cc
@@ -271,9 +271,9 @@ int MockNetworkTransaction::RestartWithCertificate(
   return net::ERR_FAILED;
 }
 
-int MockNetworkTransaction::RestartWithAuth(const string16& username,
-                                            const string16& password,
-                                            net::OldCompletionCallback* callback) {
+int MockNetworkTransaction::RestartWithAuth(
+    const net::AuthCredentials& credentials,
+    net::OldCompletionCallback* callback) {
   return net::ERR_FAILED;
 }