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

sync/internal_api/attachments/in_memory_attachment_store.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/internal_api/public/attachments/in_memory_attachment_store.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/location.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 48 matching lines @@
     }
   }
   if (!unavailable_attachments->empty()) {
     result_code = AttachmentStore::UNSPECIFIED_ERROR;
   }
   PostCallback(base::Bind(callback, result_code, base::Passed(&result_map),
                           base::Passed(&unavailable_attachments)));
 }
 
 void InMemoryAttachmentStore::Write(
+    AttachmentStore::AttachmentReferrer referrer,
     const AttachmentList& attachments,
     const AttachmentStore::WriteCallback& callback) {
   DCHECK(CalledOnValidThread());
   AttachmentList::const_iterator iter = attachments.begin();
   AttachmentList::const_iterator end = attachments.end();
   for (; iter != end; ++iter) {
     attachments_.insert(std::make_pair(iter->GetId(), *iter));
   }
   PostCallback(base::Bind(callback, AttachmentStore::SUCCESS));
 }
 
 void InMemoryAttachmentStore::Drop(
+    AttachmentStore::AttachmentReferrer referrer,
     const AttachmentIdList& ids,
     const AttachmentStore::DropCallback& callback) {
   DCHECK(CalledOnValidThread());
   AttachmentStore::Result result = AttachmentStore::SUCCESS;
   AttachmentIdList::const_iterator ids_iter = ids.begin();
   AttachmentIdList::const_iterator ids_end = ids.end();
   for (; ids_iter != ids_end; ++ids_iter) {
     AttachmentMap::iterator attachments_iter = attachments_.find(*ids_iter);
     if (attachments_iter != attachments_.end()) {
       attachments_.erase(attachments_iter);
@@ skipping 17 matching lines @@
     if (attachments_iter != attachments_.end()) {
       AppendMetadata(metadata_list.get(), attachments_iter->second);
     } else {
       result_code = AttachmentStore::UNSPECIFIED_ERROR;
     }
   }
   PostCallback(base::Bind(callback, result_code, base::Passed(&metadata_list)));
 }
 
 void InMemoryAttachmentStore::ReadAllMetadata(
+    AttachmentStore::AttachmentReferrer referrer,
     const AttachmentStore::ReadMetadataCallback& callback) {
   DCHECK(CalledOnValidThread());
   AttachmentStore::Result result_code = AttachmentStore::SUCCESS;
   scoped_ptr<AttachmentMetadataList> metadata_list(
       new AttachmentMetadataList());
 
   for (AttachmentMap::const_iterator iter = attachments_.begin();
        iter != attachments_.end(); ++iter) {
     AppendMetadata(metadata_list.get(), iter->second);
   }
   PostCallback(base::Bind(callback, result_code, base::Passed(&metadata_list)));
 }
 
 }  // namespace syncer