[Sync] Introduce AttachmentStoreForSync class

sync/internal_api/attachments/on_disk_attachment_store.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 "sync/internal_api/public/attachments/on_disk_attachment_store.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/location.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 116 matching lines @@
                       : AttachmentStore::UNSPECIFIED_ERROR;
   } else {
     *unavailable_attachments = ids;
   }
 
   PostCallback(base::Bind(callback, result_code, base::Passed(&result_map),
                           base::Passed(&unavailable_attachments)));
 }
 
 void OnDiskAttachmentStore::Write(
-    AttachmentStore::AttachmentReferrer referrer,
+    AttachmentStore::Component component,
     const AttachmentList& attachments,
     const AttachmentStore::WriteCallback& callback) {
   DCHECK(CalledOnValidThread());
   AttachmentStore::Result result_code =
       AttachmentStore::STORE_INITIALIZATION_FAILED;
 
   if (db_) {
     result_code = AttachmentStore::SUCCESS;
     AttachmentList::const_iterator iter = attachments.begin();
     const AttachmentList::const_iterator end = attachments.end();
     for (; iter != end; ++iter) {
       if (!WriteSingleAttachment(*iter))
         result_code = AttachmentStore::UNSPECIFIED_ERROR;
     }
   }
   PostCallback(base::Bind(callback, result_code));
 }
 
-void OnDiskAttachmentStore::Drop(
-    AttachmentStore::AttachmentReferrer referrer,
+void OnDiskAttachmentStore::SetReference(AttachmentStore::Component component,
+                                         const AttachmentIdList& ids) {
+  DCHECK(CalledOnValidThread());
+  DCHECK_EQ(AttachmentStore::SYNC, component);
+}
+
+void OnDiskAttachmentStore::DropReference(
+    AttachmentStore::Component component,
     const AttachmentIdList& ids,
     const AttachmentStore::DropCallback& callback) {
   DCHECK(CalledOnValidThread());
+  if (component == AttachmentStore::SYNC) {
+    // TODO(pavely): There is no reference handling implementation yet. All
+    // calls to AddReferrer are ignored. Calls to Drop coming from sync should
+    // be ignored too.
+    PostCallback(base::Bind(callback, AttachmentStore::SUCCESS));
+    return;
+  }
   AttachmentStore::Result result_code =
       AttachmentStore::STORE_INITIALIZATION_FAILED;
   if (db_) {
     result_code = AttachmentStore::SUCCESS;
     leveldb::WriteOptions write_options = MakeWriteOptions();
     AttachmentIdList::const_iterator iter = ids.begin();
     const AttachmentIdList::const_iterator end = ids.end();
     for (; iter != end; ++iter) {
       leveldb::WriteBatch write_batch;
       write_batch.Delete(MakeDataKeyFromAttachmentId(*iter));
@@ skipping 30 matching lines @@
             MakeAttachmentMetadata(*iter, record_metadata));
       } else {
         result_code = AttachmentStore::UNSPECIFIED_ERROR;
       }
     }
   }
   PostCallback(base::Bind(callback, result_code, base::Passed(&metadata_list)));
 }
 
 void OnDiskAttachmentStore::ReadAllMetadata(
-    AttachmentStore::AttachmentReferrer referrer,
+    AttachmentStore::Component component,
     const AttachmentStore::ReadMetadataCallback& callback) {
   DCHECK(CalledOnValidThread());
   AttachmentStore::Result result_code =
       AttachmentStore::STORE_INITIALIZATION_FAILED;
   scoped_ptr<AttachmentMetadataList> metadata_list(
       new AttachmentMetadataList());
 
   if (db_) {
     result_code = AttachmentStore::SUCCESS;
     scoped_ptr<leveldb::Iterator> db_iterator(
@@ skipping 184 matching lines @@
   return key;
 }
 
 AttachmentMetadata OnDiskAttachmentStore::MakeAttachmentMetadata(
     const AttachmentId& attachment_id,
     const attachment_store_pb::RecordMetadata& record_metadata) {
   return AttachmentMetadata(attachment_id, record_metadata.attachment_size());
 }
 
 }  // namespace syncer