Introduce a layering in the invalidation component as public and impl

components/invalidation/invalidation_handler.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_INVALIDATION_HANDLER_H_
-#define COMPONENTS_INVALIDATION_INVALIDATION_HANDLER_H_
-
-#include <string>
-
-#include "components/invalidation/invalidation_export.h"
-#include "components/invalidation/invalidator_state.h"
-
-namespace syncer {
-
-class ObjectIdInvalidationMap;
-
-class INVALIDATION_EXPORT InvalidationHandler {
- public:
-  InvalidationHandler();
-
-  // Called when the invalidator state changes.
-  virtual void OnInvalidatorStateChange(InvalidatorState state) = 0;
-
-  // Called when a invalidation is received.  The per-id states are in
-  // |id_state_map| and the source is in |source|.  Note that this may be
-  // called regardless of the current invalidator state.
-  virtual void OnIncomingInvalidation(
-      const ObjectIdInvalidationMap& invalidation_map) = 0;
-
-  virtual std::string GetOwnerName() const = 0;
-
- protected:
-  virtual ~InvalidationHandler();
-};
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_INVALIDATION_INVALIDATION_HANDLER_H_