Revert of Move base/prefs to components/prefs

components/prefs/pref_observer.h

Index: components/prefs/pref_observer.h
diff --git a/components/prefs/pref_observer.h b/components/prefs/pref_observer.h
deleted file mode 100644
index 5d8f5b63dc3c9cb363a546ee10ddb92787765937..0000000000000000000000000000000000000000
--- a/components/prefs/pref_observer.h
+++ /dev/null
@@ -1,21 +0,0 @@
-// Copyright (c) 2012 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 BASE_PREFS_PREF_OBSERVER_H_
-#define BASE_PREFS_PREF_OBSERVER_H_
-
-#include <string>
-
-class PrefService;
-
-// Used internally to the Prefs subsystem to pass preference change
-// notifications between PrefService, PrefNotifierImpl and
-// PrefChangeRegistrar.
-class PrefObserver {
- public:
-  virtual void OnPreferenceChanged(PrefService* service,
-                                   const std::string& pref_name) = 0;
-};
-
-#endif  // BASE_PREFS_PREF_OBSERVER_H_