Introduce a layering in the invalidation component as public and impl

components/invalidation/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_
-
-#include <map>
-#include <set>
-#include <string>
-
-#include "base/memory/scoped_ptr.h"
-#include "components/invalidation/invalidation_export.h"
-
-namespace base {
-class DictionaryValue;
-}  // namespace
-
-namespace invalidation {
-class Invalidation;
-class ObjectId;
-}  // namespace invalidation
-
-namespace syncer {
-
-class Invalidation;
-
-struct INVALIDATION_EXPORT ObjectIdLessThan {
-  bool operator()(const invalidation::ObjectId& lhs,
-                  const invalidation::ObjectId& rhs) const;
-};
-
-struct INVALIDATION_EXPORT InvalidationVersionLessThan {
-  bool operator()(const syncer::Invalidation& a,
-                  const syncer::Invalidation& b) const;
-};
-
-typedef std::set<invalidation::ObjectId, ObjectIdLessThan> ObjectIdSet;
-
-typedef std::map<invalidation::ObjectId, int, ObjectIdLessThan>
-    ObjectIdCountMap;
-
-// Caller owns the returned DictionaryValue.
-scoped_ptr<base::DictionaryValue> ObjectIdToValue(
-    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_