Add AttachmentDownloader interface, change signature of AttachmentStore::Read

sync/api/attachments/attachment_service_impl.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/api/attachments/attachment_service_impl.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "sync/api/attachments/attachment.h"
 #include "sync/internal_api/public/attachments/fake_attachment_store.h"
@@ skipping 77 matching lines @@
 void AttachmentServiceImpl::OnSyncDataUpdate(
     const AttachmentIdList& old_attachment_ids,
     const SyncData& updated_sync_data) {
   DCHECK(CalledOnValidThread());
   // TODO(maniscalco): At this point we need to ensure we write all new
   // attachments referenced by updated_sync_data to local storage and schedule
   // them up upload to the server. We also need to remove any no unreferenced
   // attachments from local storage (bug 356351).
 }
 
-void AttachmentServiceImpl::ReadDone(const GetOrDownloadCallback& callback,
-                                     const AttachmentStore::Result& result,
-                                     scoped_ptr<AttachmentMap> attachments) {
+void AttachmentServiceImpl::ReadDone(
+    const GetOrDownloadCallback& callback,
+    const AttachmentStore::Result& result,
+    scoped_ptr<AttachmentMap> attachments,
+    scoped_ptr<AttachmentIdList> unavailable_attachment_ids) {
   AttachmentService::GetOrDownloadResult get_result =
       AttachmentService::GET_UNSPECIFIED_ERROR;
   if (result == AttachmentStore::SUCCESS) {
     get_result = AttachmentService::GET_SUCCESS;
   }
   // TODO(maniscalco): Deal with case where an error occurred (bug 361251).
   base::MessageLoop::current()->PostTask(
       FROM_HERE, base::Bind(callback, get_result, base::Passed(&attachments)));
 }
 
@@ skipping 26 matching lines @@
     const AttachmentId& attachment_id) {
   // TODO(pavely): crbug/372622: Deal with UploadAttachment failures.
   if (result != AttachmentUploader::UPLOAD_SUCCESS)
     return;
   if (delegate_) {
     delegate_->OnAttachmentUploaded(attachment_id);
   }
 }
 
 }  // namespace syncer