Introduce a layering in the invalidation component as public and impl

components/invalidation/invalidator_state.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_INVALIDATOR_STATE_H_
-#define COMPONENTS_INVALIDATION_INVALIDATOR_STATE_H_
-
-#include "components/invalidation/invalidation_export.h"
-
-namespace syncer {
-
-enum InvalidatorState {
-  // Failure states
-  // --------------
-  // There is an underlying transient problem (e.g., network- or
-  // XMPP-related).
-  TRANSIENT_INVALIDATION_ERROR,
-  DEFAULT_INVALIDATION_ERROR = TRANSIENT_INVALIDATION_ERROR,
-  // Our credentials have been rejected.
-  INVALIDATION_CREDENTIALS_REJECTED,
-
-  // Invalidations are fully working.
-  INVALIDATIONS_ENABLED
-};
-
-INVALIDATION_EXPORT const char* InvalidatorStateToString(
-    InvalidatorState state);
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_INVALIDATION_INVALIDATOR_STATE_H_