Update sync API to support attachments.

sync/api/attachments/attachment.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/api/attachments/attachment.h"
 
 #include "base/logging.h"
 
 namespace syncer {
 
 Attachment::~Attachment() {}
 
 // Static.
-scoped_ptr<Attachment> Attachment::Create(
+Attachment Attachment::Create(
     const scoped_refptr<base::RefCountedMemory>& data) {
   return CreateWithId(AttachmentId::Create(), data);
 }
 
 // Static.
-scoped_ptr<Attachment> Attachment::CreateWithId(
+Attachment Attachment::CreateWithId(
     const AttachmentId& id,
     const scoped_refptr<base::RefCountedMemory>& data) {
-  return scoped_ptr<Attachment>(new Attachment(id, data)).Pass();
+  return Attachment(id, data);
 }
 
 const AttachmentId& Attachment::GetId() const { return id_; }
 
 const scoped_refptr<base::RefCountedMemory>& Attachment::GetData() const {
   return data_;
 }
 
 Attachment::Attachment(const AttachmentId& id,
                        const scoped_refptr<base::RefCountedMemory>& data)
     : id_(id), data_(data) {
   DCHECK(data);
 }
 
 }  // namespace syncer