Move undo files into //components/undo

components/undo/undo_manager_observer.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_UNDO_UNDO_MANAGER_OBSERVER_H_
-#define CHROME_BROWSER_UNDO_UNDO_MANAGER_OBSERVER_H_
+#ifndef COMPONENTS_UNDO_UNDO_MANAGER_OBSERVER_H_
+#define COMPONENTS_UNDO_UNDO_MANAGER_OBSERVER_H_
 
 // Observer for the UndoManager.
 class UndoManagerObserver {
  public:
   // Invoked when the internal state of the UndoManager has changed.
   virtual void OnUndoManagerStateChange() = 0;
 
  protected:
   virtual ~UndoManagerObserver() {}
 };
 
-#endif  // CHROME_BROWSER_UNDO_UNDO_MANAGER_OBSERVER_H_
+#endif  // COMPONENTS_UNDO_UNDO_MANAGER_OBSERVER_H_