[Sync] Convert DTCs to be not RefCounted and NonThreadSafe.

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/api/data_type_error_handler.h"
 #include "components/sync/core/base_transaction.h"
 #include "components/sync/core/change_record.h"
 #include "components/sync/core/user_share.h"
 
 namespace syncer {
-class DataTypeErrorHandler;
 class UnrecoverableErrorHandler;
 }  // namespace syncer
 
 namespace sync_driver {
 
 class ModelAssociator;
 
 // 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(syncer::DataTypeErrorHandler* error_handler);
+  explicit ChangeProcessor(
+      std::unique_ptr<syncer::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(syncer::UserShare* share_handle);
 
   // Changes have been applied to the backend model and are ready to be
@@ skipping 14 matching lines @@
 
  protected:
   // These methods are invoked by Start() and Stop() to do
   // implementation-specific work.
   virtual void StartImpl() = 0;
 
   syncer::DataTypeErrorHandler* error_handler() const;
   virtual syncer::UserShare* share_handle() const;
 
  private:
-  syncer::DataTypeErrorHandler* error_handler_;  // Guaranteed to outlive us.
+  std::unique_ptr<syncer::DataTypeErrorHandler> error_handler_;
 
   // The sync model we are processing changes from.
   syncer::UserShare* share_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(ChangeProcessor);
 };
 
 }  // namespace sync_driver
 
 #endif  // COMPONENTS_SYNC_DRIVER_CHANGE_PROCESSOR_H_