Introduce a layering in the invalidation component as public and impl

components/invalidation/base/invalidation_util.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.
 //
 // Various utilities for dealing with invalidation data types.
 
-#ifndef COMPONENTS_INVALIDATION_INVALIDATION_UTIL_H_
-#define COMPONENTS_INVALIDATION_INVALIDATION_UTIL_H_
+#ifndef COMPONENTS_INVALIDATION_BASE_INVALIDATION_UTIL_H_
+#define COMPONENTS_INVALIDATION_BASE_INVALIDATION_UTIL_H_
 
 #include <map>
 #include <set>
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
-#include "components/invalidation/invalidation_export.h"
+#include "components/invalidation/base/invalidation_export.h"
 
 namespace base {
 class DictionaryValue;
 }  // namespace
 
 namespace invalidation {
 class Invalidation;
 class ObjectId;
 }  // namespace invalidation
 
@@ skipping 21 matching lines @@
     const invalidation::ObjectId& object_id);
 
 bool ObjectIdFromValue(const base::DictionaryValue& value,
                        invalidation::ObjectId* out);
 
 INVALIDATION_EXPORT std::string ObjectIdToString(
     const invalidation::ObjectId& object_id);
 
 }  // namespace syncer
 
-#endif  // COMPONENTS_INVALIDATION_INVALIDATION_UTIL_H_
+#endif  // COMPONENTS_INVALIDATION_BASE_INVALIDATION_UTIL_H_