Revert of [Sync] Refactor AttachmentStore classes. Introduce concept of referrer.

sync/internal_api/public/attachments/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_INTERNAL_API_PUBLIC_ATTACHMENTS_ATTACHMENT_SERVICE_H_
 #define SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_ATTACHMENT_SERVICE_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 34 matching lines @@
     virtual ~Delegate() {}
 
     // Attachment is uploaded to server and attachment_id is updated with server
     // url.
     virtual void OnAttachmentUploaded(const AttachmentId& attachment_id) = 0;
   };
 
   AttachmentService();
   virtual ~AttachmentService();
 
+  // Return a pointer to the AttachmentStore owned by this object.
+  //
+  // May return NULL.
+  virtual AttachmentStore* GetStore() = 0;
+
   // See SyncData::GetOrDownloadAttachments.
   virtual void GetOrDownloadAttachments(
       const AttachmentIdList& attachment_ids,
       const GetOrDownloadCallback& callback) = 0;
 
   // Schedules the attachments identified by |attachment_ids| to be uploaded to
   // the server.
   //
   // Assumes the attachments are already in the attachment store.
   //
   // A request to upload attachments is persistent in that uploads will be
   // automatically retried if transient errors occur.
   //
   // A request to upload attachments does not persist across restarts of Chrome.
   //
   // Invokes OnAttachmentUploaded on the Delegate (if provided).
   virtual void UploadAttachments(const AttachmentIdSet& attachment_ids) = 0;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_ATTACHMENT_SERVICE_H_