Introduce a layering in the invalidation component as public and impl

components/invalidation/fake_invalidation_state_tracker.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.
-
-#ifndef COMPONENTS_INVALIDATION_FAKE_INVALIDATION_STATE_TRACKER_H_
-#define COMPONENTS_INVALIDATION_FAKE_INVALIDATION_STATE_TRACKER_H_
-
-#include "base/memory/weak_ptr.h"
-#include "components/invalidation/invalidation_state_tracker.h"
-
-namespace syncer {
-
-// InvalidationStateTracker implementation that simply keeps track of
-// the max versions and invalidation state in memory.
-class FakeInvalidationStateTracker
-    : public InvalidationStateTracker,
-      public base::SupportsWeakPtr<FakeInvalidationStateTracker> {
- public:
-  FakeInvalidationStateTracker();
-  ~FakeInvalidationStateTracker() override;
-
-  // InvalidationStateTracker implementation.
-  void ClearAndSetNewClientId(const std::string& client_id) override;
-  std::string GetInvalidatorClientId() const override;
-  void SetBootstrapData(const std::string& data) override;
-  std::string GetBootstrapData() const override;
-  void SetSavedInvalidations(const UnackedInvalidationsMap& states) override;
-  UnackedInvalidationsMap GetSavedInvalidations() const override;
-  void Clear() override;
-
-  static const int64 kMinVersion;
-
- private:
-  std::string invalidator_client_id_;
-  std::string bootstrap_data_;
-  UnackedInvalidationsMap unacked_invalidations_map_;
-};
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_INVALIDATION_FAKE_INVALIDATION_STATE_TRACKER_H_