[Sync] Refactor AttachmentStore classes. Introduce concept of referrer.

components/sync_driver/ui_data_type_controller_unittest.cc

 // 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.
 
 #include "components/sync_driver/ui_data_type_controller.h"
 
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/tracked_objects.h"
@@ skipping 39 matching lines @@
     preference_dtc_ = NULL;
     PumpLoop();
   }
 
   base::WeakPtr<syncer::SyncableService> GetSyncableServiceForType(
       syncer::ModelType type) override {
     return syncable_service_.AsWeakPtr();
   }
 
   scoped_ptr<syncer::AttachmentService> CreateAttachmentService(
-      const scoped_refptr<syncer::AttachmentStore>& attachment_store,
+      scoped_ptr<syncer::AttachmentStore> attachment_store,
       const syncer::UserShare& user_share,
       const std::string& store_birthday,
       syncer::ModelType model_type,
       syncer::AttachmentService::Delegate* delegate) override {
     return syncer::AttachmentServiceImpl::CreateForTest();
   }
 
  protected:
   void SetStartExpectations() {
     scoped_ptr<FakeGenericChangeProcessor> p(
@@ skipping 123 matching lines @@
   EXPECT_CALL(model_load_callback_, Run(_, _));
   syncer::SyncError error(FROM_HERE,
                           syncer::SyncError::DATATYPE_ERROR,
                           "error",
                           syncer::PREFERENCES);
   preference_dtc_->OnSingleDataTypeUnrecoverableError(error);
 }
 
 }  // namespace
 }  // namespace sync_driver