chrome: Cleanup class/struct forward declarations

chrome/installer/setup/app_launcher_installer.h

 // Copyright 2015 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.
 
 // The App Launcher is an adjunct product of Google Chrome, but it has a
 // distinct registry entry. The functions in this file tap into various points
 // in installer flow to update the App Launcher's registry, including the
 // removal of deprecated app commands. This concentrates ugly code to to one
 // place to facilitate future refactoring.
 
 #ifndef CHROME_INSTALLER_SETUP_APP_LAUNCHER_INSTALLER_H_
 #define CHROME_INSTALLER_SETUP_APP_LAUNCHER_INSTALLER_H_
 
 #if defined(GOOGLE_CHROME_BUILD)
 
 #include <windows.h>
 
 namespace base {
 class FilePath;
-class Version;
 }  // namespace base
 
 class WorkItemList;
 
 namespace installer {
 
 class InstallerState;
 
 // Remove App Launcher's registry key, so it is in sync with Google Chrome's.
 // Note: The key is added by App Launcher in SetDidRunForNDayActiveStats().
 void RemoveAppLauncherVersionKey(HKEY reg_root);
 
 // Adds work item to unconditionally remove legacy executables.
 void AddRemoveLegacyAppHostExeWorkItems(const base::FilePath& target_path,
                                         const base::FilePath& temp_path,
                                         WorkItemList* list);
 
 // Adds work item to unconditionally remove legacy app commands like
 // "install-application", "install-extension", and
 // "quick-enable-application-host".
 void AddRemoveLegacyAppCommandsWorkItems(
     const InstallerState& installer_state,
     WorkItemList* work_item_list);
 
 }  // namespace installer
 
 #endif  // defined(GOOGLE_CHROME_BUILD)
 
 #endif  // CHROME_INSTALLER_SETUP_APP_LAUNCHER_INSTALLER_H_