Checkpointing some Sync Attachment work. Added SyncAttachment and SyncAttachmentId.

sync/protocol/proto_value_conversions.cc

Index: sync/protocol/proto_value_conversions.cc
diff --git a/sync/protocol/proto_value_conversions.cc b/sync/protocol/proto_value_conversions.cc
index a7ccdf23978a5f3d108c3aaa0ce88737f3e900aa..4b7e4956d80e46cdb144983224826c4e3e28b601 100644
--- a/sync/protocol/proto_value_conversions.cc
+++ b/sync/protocol/proto_value_conversions.cc
@@ -1024,6 +1024,13 @@ base::DictionaryValue* ClientConfigParamsToValue(
   return value;
 }
 
+base::DictionaryValue* SyncAttachmentIdToValue(
+    const sync_pb::SyncAttachmentId& proto) {
+  base::DictionaryValue* value = new base::DictionaryValue();
+  SET_STR(unique_id);
+  return value;
+}
+
 #undef SET
 #undef SET_REP