Fix fields of SendTabToSelfSpecifics proto not shown in sync-internals

This CL makes sure the `opened` and `notification_dismissed` fields are
shown in the "Sync Node Browser" tab of chrome://sync-internals by
adding some missing code to proto_visitors.h.

Bug: 1164334
Change-Id: I226b37e07709acd8eb164f67c85a22d72cc70e5d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2616201Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Victor Vianna <victorvianna@google.com>
Cr-Commit-Position: refs/heads/master@{#841474}

components/sync/protocol/proto_visitors.h

@@ -818,6 +818,8 @@ VISIT_PROTO_FIELDS(const sync_pb::SendTabToSelfSpecifics& proto) {
   VISIT(navigation_time_usec);
   VISIT(device_name);
   VISIT(target_device_sync_cache_guid);
+  VISIT(opened);
+  VISIT(notification_dismissed);
 }
 
 VISIT_PROTO_FIELDS(const sync_pb::SessionHeader& proto) {