Invoke AttachmentUploader and update AttachmentIds.

sync/protocol/attachments.proto

 // 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.
 //
 // Sync protocol for attachments.
 
 // Update proto_{value,enum}_conversions{.h,.cc,_unittest.cc} if you change any
 // fields in this file.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 option retain_unknown_fields = true;
 
 package sync_pb;
 
 // Identifies an attachment.
 message AttachmentIdProto {
   // Uniquely identifies the attachment. Two attachments with the same unique_id
   // are considered equivalent.
   optional string unique_id = 1;
+  // Server url to download attachment data.
+  optional string url = 3;

[maniscalco, 2014/05/09 18:12:11]

URL may be too specific because it encodes both the service endpoint and the
attachment.  I'd like to explore some options:

Instead of url, we could store some blob id and have the client know which
endpoint to use (prod, test, staging, etc.).  The downloader would then need to
know how to form the URL for retrieval.

Another approach would be to replace url with a backend specific type (a proto
message) that's logically private to AttachmentUploader/Downloader.

Let's chat more about this in person.

[pavely, 2014/05/13 23:06:44]

I needed to start with something so I put url.
We need to decide what's it going to be, it needs to be flexible for future
change of attachment server.
Two options:
1. Have one string field and let code in AttachmentService interpret it.
2. Have attachment server specific proto and abandon it if we decide to migrate
to different attachment server.
I think #2 is simpler.

For now let me just remove this field from this change. We'll add it when we
know what it will look like.
On 2014/05/09 18:12:11, maniscalco wrote:

[maniscalco, 2014/05/15 20:09:28]

SGTM

On 2014/05/13 23:06:44, pavely wrote:

 }
 
 // Metadata for a single attachment.
 message AttachmentMetadataRecord {
   optional AttachmentIdProto id = 1;
   // Indicates we know this attachment exists on the server.
   optional bool is_on_server = 2;
 }
 
 // A collection of attachment metadata. This proto is part of EntryKernel's "on
 // disk" representation. Private to sync.
 message AttachmentMetadata {
   // One record per attachment.
   repeated AttachmentMetadataRecord record = 1;
 }