chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/extension_system_impl.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_EXTENSIONS_EXTENSION_SYSTEM_IMPL_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_SYSTEM_IMPL_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/one_shot_event.h"
 
 class Profile;
-class ValueStore;
 
 #if defined(OS_CHROMEOS)
 namespace chromeos {
 class DeviceLocalAccountManagementPolicyProvider;
 class SigninScreenPolicyProvider;
 }
 #endif  // defined(OS_CHROMEOS)
 
 namespace extensions {
 
@@ skipping 125 matching lines @@
   Profile* profile_;
 
   Shared* shared_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionSystemImpl);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_SYSTEM_IMPL_H_