Cleanup: Remove unneeded forward declarations in chrome/installer.

chrome/installer/setup/install.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.
 //
 // This file contains the specification of setup main functions.
 
 #ifndef CHROME_INSTALLER_SETUP_INSTALL_H_
 #define CHROME_INSTALLER_SETUP_INSTALL_H_
 #pragma once
 
 #include <string>
 #include <vector>
 
 #include "base/version.h"
 #include "chrome/installer/util/product.h"
 #include "chrome/installer/util/util_constants.h"
 
 class FilePath;
-class WorkItemList;
 
 namespace installer {
 
 class InstallationState;
 class InstallerState;
 class MasterPreferences;
 
 // This function installs or updates a new version of Chrome. It returns
 // install status (failed, new_install, updated etc).
 //
@@ skipping 17 matching lines @@
     const FilePath& setup_path,
     const FilePath& archive_path,
     const FilePath& install_temp_path,
     const FilePath& prefs_path,
     const installer::MasterPreferences& prefs,
     const Version& new_version);
 
 }  // namespace installer
 
 #endif  // CHROME_INSTALLER_SETUP_INSTALL_H_