sync: Enable typed tombstones commits

sync/engine/commit_util.cc

Index: sync/engine/commit_util.cc
diff --git a/sync/engine/commit_util.cc b/sync/engine/commit_util.cc
index 45bc2bbf1e219f71fb5ea4b4ce5f07486fed9357..36b7c06b9c8c0dd9557ff53b57ac4910960a1532 100644
--- a/sync/engine/commit_util.cc
+++ b/sync/engine/commit_util.cc
@@ -182,6 +182,10 @@ void BuildCommitItem(
   // Deletion is final on the server, let's move things and then delete them.
   if (meta_entry.GetIsDel()) {
     sync_entry->set_deleted(true);
+
+    sync_pb::EntitySpecifics type_only_specifics;
+    AddDefaultFieldValue(meta_entry.GetModelType(),

[haitaol1, 2014/05/19 21:59:12]

Will it cause parse failure on server if required field in data type specifics
is not set?

[albertb, 2014/05/19 22:02:57]

It would, but as far as I can tell, there are no required fields in any of the
specifics messages.

[rlarocque, 2014/05/19 22:14:57]

That's a good point.  It probably would cause a parse failure.  It might even
cause an error earlier, when we try to serialize the incomplete proto.

Fortunately, there are no required fields in specifics.

If there were required fields, I think it would be AddDefaultFieldValue's
responsibility to populate them with sensible defaults.  Otherwise, it would
likely cause problems elsewhere, too.

[haitaol1, 2014/05/19 22:39:05]

Can you add a test that calls AddDefaultFieldValue on all data types and
verifies for the modified specifics:
1. No parse error.
2. Correct model type can be deducted.

On 2014/05/19 22:14:57, rlarocque wrote:

[rlarocque, 2014/05/19 23:51:28]

Done.

+                         sync_entry->mutable_specifics());
   } else {
     SetEntrySpecifics(meta_entry, sync_entry);
   }