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

components/prefs/mock_pref_change_callback.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_MOCK_PREF_CHANGE_CALLBACK_H_
-#define COMPONENTS_PREFS_MOCK_PREF_CHANGE_CALLBACK_H_
+#ifndef BASE_PREFS_MOCK_PREF_CHANGE_CALLBACK_H_
+#define BASE_PREFS_MOCK_PREF_CHANGE_CALLBACK_H_
 
 #include <string>
 
 #include "components/prefs/pref_change_registrar.h"
 #include "components/prefs/pref_service.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
 using testing::Pointee;
 using testing::Property;
 using testing::Truly;
@@ skipping 24 matching lines @@
 
   MOCK_METHOD1(OnPreferenceChanged, void(const std::string&));
 
   void Expect(const std::string& pref_name,
               const base::Value* value);
 
  private:
   PrefService* prefs_;
 };
 
-#endif  // COMPONENTS_PREFS_MOCK_PREF_CHANGE_CALLBACK_H_
+#endif  // BASE_PREFS_MOCK_PREF_CHANGE_CALLBACK_H_