chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/login/ui/mock_login_display.h

 // Copyright 2014 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_UI_MOCK_LOGIN_DISPLAY_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_UI_MOCK_LOGIN_DISPLAY_H_
 
 #include "base/macros.h"
 #include "chrome/browser/chromeos/login/ui/login_display.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
-class AccountId;
-
 namespace chromeos {
 
 class MockLoginDisplay : public LoginDisplay {
  public:
   MockLoginDisplay();
   ~MockLoginDisplay();
 
   MOCK_METHOD0(ClearAndEnablePassword, void(void));
   MOCK_METHOD4(Init, void(const user_manager::UserList&, bool, bool, bool));
   MOCK_METHOD0(OnPreferencesChanged, void(void));
   MOCK_METHOD1(OnUserImageChanged, void(const user_manager::User&));
   MOCK_METHOD1(SetUIEnabled, void(bool));
   MOCK_METHOD3(ShowError, void(int, int, HelpAppLauncher::HelpTopic));
   MOCK_METHOD1(ShowErrorScreen, void(LoginDisplay::SigninError));
   MOCK_METHOD2(ShowPasswordChangedDialog, void(bool, const std::string&));
   MOCK_METHOD1(ShowSigninUI, void(const std::string&));
   MOCK_METHOD0(ShowWhitelistCheckFailedError, void(void));
   MOCK_METHOD0(ShowUnrecoverableCrypthomeErrorDialog, void());
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockLoginDisplay);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_UI_MOCK_LOGIN_DISPLAY_H_