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

sync/internal_api/attachments/attachment_store_test_template.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 SYNC_INTERNAL_API_ATTACHMENTS_ATTACHMENT_STORE_TEST_TEMPLATE_H_
 #define SYNC_INTERNAL_API_ATTACHMENTS_ATTACHMENT_STORE_TEST_TEMPLATE_H_
 
 #include "sync/api/attachments/attachment_store.h"
 
 #include "base/bind.h"
@@ skipping 29 matching lines @@
 namespace syncer {
 
 const char kTestData1[] = "test data 1";
 const char kTestData2[] = "test data 2";
 
 template <typename AttachmentStoreFactory>
 class AttachmentStoreTest : public testing::Test {
  protected:
   AttachmentStoreFactory attachment_store_factory;
   base::MessageLoop message_loop;
-  scoped_refptr<AttachmentStore> store;
+  scoped_ptr<AttachmentStore> store;
   AttachmentStore::Result result;
   scoped_ptr<AttachmentMap> attachments;
   scoped_ptr<AttachmentIdList> failed_attachment_ids;
   scoped_ptr<AttachmentMetadataList> attachment_metadata;
 
   AttachmentStore::ReadCallback read_callback;
   AttachmentStore::WriteCallback write_callback;
   AttachmentStore::DropCallback drop_callback;
   AttachmentStore::ReadMetadataCallback read_metadata_callback;
 
@@ skipping 330 matching lines @@
                            Write_RoundTrip,
                            Read_OneNotFound,
                            Drop_DropTwoButOnlyOneExists,
                            Drop_DoesNotExist,
                            ReadMetadata,
                            ReadAllMetadata);
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_ATTACHMENTS_ATTACHMENT_STORE_TEST_TEMPLATE_H_