Keep track of which attachments are referenced by which sync entries.

sync/api/attachments/fake_attachment_service.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_API_ATTACHMENTS_FAKE_ATTACHMENT_SERVICE_H_
 #define SYNC_API_ATTACHMENTS_FAKE_ATTACHMENT_SERVICE_H_
 
 #include "base/memory/weak_ptr.h"
 #include "base/threading/non_thread_safe.h"
 #include "sync/api/attachments/attachment_service.h"
@@ skipping 11 matching lines @@
 
   // Create a FakeAttachmentService suitable for use in tests.
   static scoped_ptr<syncer::AttachmentService> CreateForTest();
 
   // AttachmentService implementation.
   virtual void GetOrDownloadAttachments(const AttachmentIdList& attachment_ids,
                                         const GetOrDownloadCallback& callback)
       OVERRIDE;
   virtual void DropAttachments(const AttachmentIdList& attachment_ids,
                                const DropCallback& callback) OVERRIDE;
-  virtual void OnSyncDataAdd(const SyncData& sync_data) OVERRIDE;
+  virtual void StoreAttachments(const AttachmentList& attachments,
+                                const StoreCallback& callback) OVERRIDE;
   virtual void OnSyncDataDelete(const SyncData& sync_data) OVERRIDE;
   virtual void OnSyncDataUpdate(const AttachmentIdList& old_attachment_ids,
                                 const SyncData& updated_sync_data) OVERRIDE;
 
  private:
   void ReadDone(const GetOrDownloadCallback& callback,
                 const AttachmentStore::Result& result,
                 scoped_ptr<AttachmentMap> attachments);
   void DropDone(const DropCallback& callback,
                 const AttachmentStore::Result& result);
+  void WriteDone(const StoreCallback& callback,
+                 const AttachmentStore::Result& result);
 
   const scoped_ptr<AttachmentStore> attachment_store_;
   // Must be last data member.
   base::WeakPtrFactory<FakeAttachmentService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeAttachmentService);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_API_ATTACHMENTS_FAKE_ATTACHMENT_SERVICE_H_