Introduce a layering in the invalidation component as public and impl

components/invalidation/invalidator.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.
-//
-// Interface to the invalidator, which is an object that receives
-// invalidations for registered object IDs. The corresponding
-// InvalidationHandler is notifier when such an event occurs.
-
-#ifndef COMPONENTS_INVALIDATION_INVALIDATOR_H_
-#define COMPONENTS_INVALIDATION_INVALIDATOR_H_
-
-#include <string>
-
-#include "base/callback.h"
-#include "components/invalidation/invalidation_export.h"
-#include "components/invalidation/invalidation_util.h"
-#include "components/invalidation/invalidator_state.h"
-
-namespace syncer {
-class InvalidationHandler;
-
-class INVALIDATION_EXPORT Invalidator {
- public:
-  Invalidator();
-  virtual ~Invalidator();
-
-  // Clients should follow the pattern below:
-  //
-  // When starting the client:
-  //
-  //   invalidator->RegisterHandler(client_handler);
-  //
-  // When the set of IDs to register changes for the client during its lifetime
-  // (i.e., between calls to RegisterHandler(client_handler) and
-  // UnregisterHandler(client_handler):
-  //
-  //   invalidator->UpdateRegisteredIds(client_handler, client_ids);
-  //
-  // When shutting down the client for profile shutdown:
-  //
-  //   invalidator->UnregisterHandler(client_handler);
-  //
-  // Note that there's no call to UpdateRegisteredIds() -- this is because the
-  // invalidation API persists registrations across browser restarts.
-  //
-  // When permanently shutting down the client, e.g. when disabling the related
-  // feature:
-  //
-  //   invalidator->UpdateRegisteredIds(client_handler, ObjectIdSet());
-  //   invalidator->UnregisterHandler(client_handler);
-  //
-  // It is an error to have registered handlers when an invalidator is
-  // destroyed; clients must ensure that they unregister themselves
-  // before then.
-
-  // Starts sending notifications to |handler|.  |handler| must not be NULL,
-  // and it must not already be registered.
-  virtual void RegisterHandler(InvalidationHandler* handler) = 0;
-
-  // Updates the set of ObjectIds associated with |handler|.  |handler| must
-  // not be NULL, and must already be registered.  An ID must be registered for
-  // at most one handler. If ID is already registered function returns false.
-  virtual bool UpdateRegisteredIds(InvalidationHandler* handler,
-                                   const ObjectIdSet& ids)
-      WARN_UNUSED_RESULT = 0;
-
-  // Stops sending notifications to |handler|.  |handler| must not be NULL, and
-  // it must already be registered.  Note that this doesn't unregister the IDs
-  // associated with |handler|.
-  virtual void UnregisterHandler(InvalidationHandler* handler) = 0;
-
-  // Returns the current invalidator state.  When called from within
-  // InvalidationHandler::OnInvalidatorStateChange(), this must return
-  // the updated state.
-  virtual InvalidatorState GetInvalidatorState() const = 0;
-
-  // The observers won't be notified of any notifications until
-  // UpdateCredentials is called at least once. It can be called more than
-  // once.
-  virtual void UpdateCredentials(
-      const std::string& email, const std::string& token) = 0;
-
-  // Requests internal detailed status to be posted back to the callback.
-  virtual void RequestDetailedStatus(
-      base::Callback<void(const base::DictionaryValue&)> callback) const = 0;
-};
-}  // namespace syncer
-
-#endif  // COMPONENTS_INVALIDATION_INVALIDATOR_H_