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

sync/api/attachments/attachment_service_proxy.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_ATTACHMENT_SERVICE_PROXY_H_
 #define SYNC_API_ATTACHMENTS_ATTACHMENT_SERVICE_PROXY_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 40 matching lines @@
       const base::WeakPtr<syncer::AttachmentService>& wrapped);
 
   virtual ~AttachmentServiceProxy();
 
   // 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& attachment,
+                                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;
 
  protected:
   // Core does the work of proxying calls to AttachmentService methods from one
   // thread to another so AttachmentServiceProxy can be an easy-to-use,
   // non-ref-counted A ref-counted class.
   //
   // Callback from AttachmentService are proxied back using free functions
@@ skipping 10 matching lines @@
    public:
     // Construct an AttachmentServiceProxyCore that forwards calls to |wrapped|.
     Core(const base::WeakPtr<syncer::AttachmentService>& wrapped);
 
     // 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& attachment,
+                                  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;
 
    protected:
     friend class base::RefCountedThreadSafe<Core>;
     virtual ~Core();
 
    private:
     base::WeakPtr<AttachmentService> wrapped_;
 
     DISALLOW_COPY_AND_ASSIGN(Core);
   };
 
   // Used in tests to create an AttachmentServiceProxy with a custom Core.
   AttachmentServiceProxy(
       const scoped_refptr<base::SequencedTaskRunner>& wrapped_task_runner,
       const scoped_refptr<Core>& core);
 
  private:
   scoped_refptr<base::SequencedTaskRunner> wrapped_task_runner_;
   scoped_refptr<Core> core_;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_SERVICE_PROXY_H_