Fix the clang bot.

chrome/browser/chromeos/login/mock_authenticator.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_LOGIN_MOCK_AUTHENTICATOR_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_MOCK_AUTHENTICATOR_H_
 #pragma once
 
 #include <string>
 
@@ skipping 49 matching lines @@
 
   virtual void ResyncEncryptedData(
       const GaiaAuthConsumer::ClientLoginResult& credentials) {}
 
   virtual void RetryAuth(Profile* profile,
                          const std::string& username,
                          const std::string& password,
                          const std::string& login_token,
                          const std::string& login_captcha) {}
 
-  virtual std::string EncryptToken(const std::string& token) {
-    return std::string();
-  }
+  virtual std::string EncryptToken(const std::string& token);
 
-  virtual std::string DecryptToken(const std::string& encrypted_token) {
-    return std::string();
-  }
+  virtual std::string DecryptToken(const std::string& encrypted_token);
 
   virtual void VerifyOAuth1AccessToken(const std::string& oauth1_access_token,
                                        const std::string& oauth1_secret) {}
 
  private:
   std::string expected_username_;
   std::string expected_password_;
 
   DISALLOW_COPY_AND_ASSIGN(MockAuthenticator);
 };
@@ skipping 47 matching lines @@
   std::string expected_password_;
   std::string auth_token_;
   chromeos::BackgroundView* background_view_;
 
   DISALLOW_COPY_AND_ASSIGN(MockLoginUtils);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_MOCK_AUTHENTICATOR_H_