Keep only base/extractor.[cc|h].

base/shutdown_callback.h

-// Copyright 2007-2009 Google Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-// ========================================================================
-
-//
-// ShutdownCallBack monitors a shutdown event.
-
-#ifndef OMAHA_COMMON_SHUTDOWN_CALLBACK_H__
-#define OMAHA_COMMON_SHUTDOWN_CALLBACK_H__
-
-#include <windows.h>
-
-namespace omaha {
-
-class ShutdownCallback {
- public:
-  virtual ~ShutdownCallback() {}
-  virtual HRESULT Shutdown() = 0;
-};
-
-}  // namespace omaha
-
-#endif  // OMAHA_COMMON_SHUTDOWN_CALLBACK_H__
-