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

net/http/http_auth_controller.h

Index: net/http/http_auth_controller.h
diff --git a/net/http/http_auth_controller.h b/net/http/http_auth_controller.h
index 45a13394b558be5e71e87aaa2b3fff109b933610..7355e59633bb1bc05d570044d2ac920768ce64c0 100644
--- a/net/http/http_auth_controller.h
+++ b/net/http/http_auth_controller.h
@@ -23,6 +23,7 @@
 namespace net {
 
 class AuthChallengeInfo;
+class AuthCredentials;
 class HttpAuthHandler;
 class HttpAuthHandlerFactory;
 class HttpAuthCache;
@@ -62,8 +63,7 @@ class NET_EXPORT_PRIVATE HttpAuthController
                                   const BoundNetLog& net_log);
 
   // Store the supplied credentials and prepare to restart the auth.
-  virtual void ResetAuth(const string16& username,
-                         const string16& password);
+  virtual void ResetAuth(const AuthCredentials& credentials);
 
   virtual bool HaveAuthHandler() const;