Revert of Delete base/prefs and update callers to use components.

components/prefs/pref_notifier_impl.h

 // Copyright (c) 2011 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 COMPONENTS_PREFS_PREF_NOTIFIER_IMPL_H_
-#define COMPONENTS_PREFS_PREF_NOTIFIER_IMPL_H_
+#ifndef BASE_PREFS_PREF_NOTIFIER_IMPL_H_
+#define BASE_PREFS_PREF_NOTIFIER_IMPL_H_
 
 #include <list>
 #include <string>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/containers/hash_tables.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "base/threading/thread_checker.h"
 #include "components/prefs/base_prefs_export.h"
 #include "components/prefs/pref_notifier.h"
 #include "components/prefs/pref_observer.h"
 
 class PrefService;
 
 // The PrefNotifier implementation used by the PrefService.
-class COMPONENTS_PREFS_EXPORT PrefNotifierImpl
+class BASE_PREFS_EXPORT PrefNotifierImpl
     : public NON_EXPORTED_BASE(PrefNotifier) {
  public:
   PrefNotifierImpl();
   explicit PrefNotifierImpl(PrefService* pref_service);
   ~PrefNotifierImpl() override;
 
   // If the pref at the given path changes, we call the observer's
   // OnPreferenceChanged method.
   void AddPrefObserver(const std::string& path, PrefObserver* observer);
   void RemovePrefObserver(const std::string& path, PrefObserver* observer);
@@ skipping 29 matching lines @@
   PrefService* pref_service_;
 
   PrefObserverMap pref_observers_;
   PrefInitObserverList init_observers_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefNotifierImpl);
 };
 
-#endif  // COMPONENTS_PREFS_PREF_NOTIFIER_IMPL_H_
+#endif  // BASE_PREFS_PREF_NOTIFIER_IMPL_H_