Do not update AttachmentIds after uploading attachments to sync server.

sync/api/attachments/attachment_uploader.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_UPLOADER_H_
 #define SYNC_API_ATTACHMENTS_ATTACHMENT_UPLOADER_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 16 matching lines @@
       UploadCallback;
 
   AttachmentUploader();
   virtual ~AttachmentUploader();
 
   // Upload |attachment| and invoke |callback| when done.
   //
   // |callback| will be invoked when the operation has completed (successfully
   // or otherwise).
   //
-  // |callback| will receive an UploadResult code and an updated AttachmentId
-  // containing the server address of the newly uploaded attachment.
+  // |callback| will receive an UploadResult code and the AttachmentId of the
+  // newly uploaded attachment.
   virtual void UploadAttachment(const Attachment& attachment,
                                 const UploadCallback& callback) = 0;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_UPLOADER_H_