[Sync] Move ChangeProcessor to model/.

components/sync/driver/change_processor.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_SYNC_DRIVER_CHANGE_PROCESSOR_H_
-#define COMPONENTS_SYNC_DRIVER_CHANGE_PROCESSOR_H_
-
-#include <stdint.h>
-
-#include <memory>
-
-#include "base/macros.h"
-#include "components/sync/model/data_type_error_handler.h"
-#include "components/sync/syncable/base_transaction.h"
-#include "components/sync/syncable/change_record.h"
-#include "components/sync/syncable/user_share.h"
-
-namespace syncer {
-
-class ModelAssociator;
-class UnrecoverableErrorHandler;
-
-// An interface used to apply changes from the sync model to the browser's
-// native model.  This does not currently distinguish between model data types.
-class ChangeProcessor {
- public:
-  explicit ChangeProcessor(std::unique_ptr<DataTypeErrorHandler> error_handler);
-  virtual ~ChangeProcessor();
-
-  // Call when the processor should accept changes from either provided model
-  // and apply them to the other.  Both the native model and sync_api are
-  // expected to be initialized and loaded.  You must have set a valid
-  // ModelAssociator and UnrecoverableErrorHandler before using this method, and
-  // the two models should be associated w.r.t the ModelAssociator provided.
-  void Start(UserShare* share_handle);
-
-  // Changes have been applied to the backend model and are ready to be
-  // applied to the frontend model.
-  virtual void ApplyChangesFromSyncModel(
-      const BaseTransaction* trans,
-      int64_t model_version,
-      const ImmutableChangeRecordList& changes) = 0;
-
-  // The changes found in ApplyChangesFromSyncModel may be too slow to be
-  // performed while holding a [Read/Write]Transaction lock or may interact
-  // with another thread, which might itself be waiting on the transaction lock,
-  // putting us at risk of deadlock.
-  // This function is called once the transactional lock is released and it is
-  // safe to perform inter-thread or slow I/O operations. Note that not all
-  // datatypes need this, so we provide an empty default version.
-  virtual void CommitChangesFromSyncModel();
-
- protected:
-  // These methods are invoked by Start() and Stop() to do
-  // implementation-specific work.
-  virtual void StartImpl() = 0;
-
-  DataTypeErrorHandler* error_handler() const;
-  virtual UserShare* share_handle() const;
-
- private:
-  std::unique_ptr<DataTypeErrorHandler> error_handler_;
-
-  // The sync model we are processing changes from.
-  UserShare* share_handle_;
-
-  DISALLOW_COPY_AND_ASSIGN(ChangeProcessor);
-};
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_SYNC_DRIVER_CHANGE_PROCESSOR_H_