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

components/sync_driver/device_info_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 "base/bind.h"
 #include "base/callback.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "components/sync_driver/device_info_data_type_controller.h"
@@ skipping 47 matching lines @@
   }
 
   base::WeakPtr<syncer::SyncableService> GetSyncableServiceForType(
       syncer::ModelType type) override {
     // Shouldn't be called for this test.
     NOTREACHED();
     return base::WeakPtr<syncer::SyncableService>();
   }
 
   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 {
     // Shouldn't be called for this test.
     NOTREACHED();
     return scoped_ptr<syncer::AttachmentService>();
   }
 
   void OnLoadFinished(syncer::ModelType type, syncer::SyncError error) {
@@ skipping 60 matching lines @@
   controller_->Stop();
   // Destroy |local_device_| and |controller_| out of order
   // to verify that the controller doesn't crash in the destructor.
   local_device_.reset();
   controller_ = NULL;
 }
 
 }  // namespace
 
 }  // namespace sync_driver