Update Commit and GetUpdatesResponse messages to include attachment ids.

sync/internal_api/sync_manager_impl.cc

Index: sync/internal_api/sync_manager_impl.cc
diff --git a/sync/internal_api/sync_manager_impl.cc b/sync/internal_api/sync_manager_impl.cc
index 256a5c9fdd4fc729720227c65405da8038895155..a64c9416ace8e1634c87d1cc3058667eff434d9a 100644
--- a/sync/internal_api/sync_manager_impl.cc
+++ b/sync/internal_api/sync_manager_impl.cc
@@ -226,6 +226,10 @@ bool SyncManagerImpl::VisiblePropertiesDiffer(
                          b.ref(syncable::SPECIFICS))) {
     return true;
   }
+  if (!AreAttachmentMetadataEqual(a.ref(syncable::ATTACHMENT_METADATA),
+                                  b.ref(syncable::ATTACHMENT_METADATA))) {
+    return true;
+  }
   // We only care if the name has changed if neither specifics is encrypted
   // (encrypted nodes blow away the NON_UNIQUE_NAME).
   if (!a_specifics.has_encrypted() && !b_specifics.has_encrypted() &&