Move AttachmentStore ownership to datatype

sync/api/syncable_service.h

 // Copyright 2012 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_API_SYNCABLE_SERVICE_H_
 #define SYNC_API_SYNCABLE_SERVICE_H_
 
 #include <vector>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "sync/api/attachments/attachment_store.h"
 #include "sync/api/sync_change_processor.h"
 #include "sync/api/sync_data.h"
 #include "sync/api/sync_error.h"
 #include "sync/api/sync_merge_result.h"
 #include "sync/base/sync_export.h"
 #include "sync/internal_api/public/base/model_type.h"
 
 namespace syncer {
 
 class SyncErrorFactory;
@@ skipping 34 matching lines @@
 
   // SyncChangeProcessor interface.
   // Process a list of new SyncChanges and update the local data as necessary.
   // Returns: A default SyncError (IsSet() == false) if no errors were
   //          encountered, and a filled SyncError (IsSet() == true)
   //          otherwise.
   virtual SyncError ProcessSyncChanges(
       const tracked_objects::Location& from_here,
       const SyncChangeList& change_list) OVERRIDE = 0;
 
+  // Returns AttachmentStore used by datatype. Attachment store is used by sync
+  // when uploading or downloading attachments.
+  // GetAttachmentStore is called right before MergeDataAndStartSyncing. If at
+  // that time GetAttachmentStore returns NULL then datatype is considered not
+  // using attachments and all attempts to upload/download attachments will
+  // fail. Default implementation returns NULL. Datatype that uses sync
+  // attachemnts should create attachment store and implement GetAttachmentStore
+  // to return pointer to it.
+  virtual scoped_refptr<AttachmentStore> GetAttachmentStore();
+
  protected:
   virtual ~SyncableService();
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_API_SYNCABLE_SERVICE_H_