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

base/store_watcher.h

-// Copyright 2006-2009 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.
-// ========================================================================
-
-//
-// A simple interface for monitoring changes
-// happening to a store.
-//
-#ifndef OMAHA_COMMON_STORE_WATCHER_H_
-#define OMAHA_COMMON_STORE_WATCHER_H_
-
-#include "omaha/base/synchronized.h"
-
-namespace omaha {
-
-// Allows for monitoring changes happening to a store
-// (independant of what the underlying store is).
-class StoreWatcher {
- public:
-  StoreWatcher() {}
-  virtual ~StoreWatcher() {}
-
-  // Called to create/reset the event that gets signaled
-  // any time the store changes.  Access the created
-  // event using change_event().
-  virtual HRESULT EnsureEventSetup() = 0;
-
-  // Indicates if any changes have occured
-  bool HasChangeOccurred() const {
-    return IsHandleSignaled(change_event());
-  }
-
-  // Get the event that is signaled on store changes.
-  // Note:
-  //   * This event will remain constant until the class is destroyed.
-  //   * One should call EnsureEventSetup to set-up the event.
-  //   * The event is only signaled on the next change and remains signaled.
-  //     Do not call ::ResetEvent(). Call EnsureEventSetup() to reset
-  //     the event and wait for more changes.
-  virtual HANDLE change_event() const = 0;
-
- private:
-  DISALLOW_EVIL_CONSTRUCTORS(StoreWatcher);
-};
-
-}  // namespace omaha
-
-#endif  // OMAHA_COMMON_STORE_WATCHER_H_