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

net/http/http_auth_handler_mock.h

Index: net/http/http_auth_handler_mock.h
diff --git a/net/http/http_auth_handler_mock.h b/net/http/http_auth_handler_mock.h
index a78b87645bc748d207c72de4723a6b3cdeaf09a4..5c87c2134e20620064c91ecf8e4382252d277f7c 100644
--- a/net/http/http_auth_handler_mock.h
+++ b/net/http/http_auth_handler_mock.h
@@ -10,7 +10,6 @@
 
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
-#include "base/string16.h"
 #include "googleurl/src/gurl.h"
 #include "net/http/http_auth_handler.h"
 #include "net/http/http_auth_handler_factory.h"
@@ -97,8 +96,7 @@ class HttpAuthHandlerMock : public HttpAuthHandler {
  protected:
   virtual bool Init(HttpAuth::ChallengeTokenizer* challenge);
 
-  virtual int GenerateAuthTokenImpl(const string16* username,
-                                    const string16* password,
+  virtual int GenerateAuthTokenImpl(const AuthCredentials* credentials,
                                     const HttpRequestInfo* request,
                                     OldCompletionCallback* callback,
                                     std::string* auth_token);