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

components/prefs/pref_value_map.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_VALUE_MAP_H_
-#define COMPONENTS_PREFS_PREF_VALUE_MAP_H_
+#ifndef BASE_PREFS_PREF_VALUE_MAP_H_
+#define BASE_PREFS_PREF_VALUE_MAP_H_
 
 #include <string>
 #include <vector>
 
 #include "base/containers/scoped_ptr_hash_map.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "components/prefs/base_prefs_export.h"
 
 namespace base {
 class Value;
 }
 
 // A generic string to value map used by the PrefStore implementations.
-class COMPONENTS_PREFS_EXPORT PrefValueMap {
+class BASE_PREFS_EXPORT PrefValueMap {
  public:
   using Map = base::ScopedPtrHashMap<std::string, scoped_ptr<base::Value>>;
   using iterator = Map::iterator;
   using const_iterator = Map::const_iterator;
 
   PrefValueMap();
   virtual ~PrefValueMap();
 
   // Gets the value for |key| and stores it in |value|. Ownership remains with
   // the map. Returns true if a value is present. If not, |value| is not
@@ skipping 49 matching lines @@
   // only in one of the maps.
   void GetDifferingKeys(const PrefValueMap* other,
                         std::vector<std::string>* differing_keys) const;
 
  private:
   Map prefs_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefValueMap);
 };
 
-#endif  // COMPONENTS_PREFS_PREF_VALUE_MAP_H_
+#endif  // BASE_PREFS_PREF_VALUE_MAP_H_