Relax DCHECKs about non_unique_name

Nothing really guarantees that a SyncableService (or a remote device)
populates the non-unique name with an empty string, so let's relax the
DCHECKs although they don't seem to fail in practice.

Bug: 870624
Change-Id: If26df0329c9749c0c2eb6b0768b8ae544b1c3879
Reviewed-on: https://chromium-review.googlesource.com/c/1442653Reviewed-by: Jan Krcal <jkrcal@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626992}

components/sync/model_impl/syncable_service_based_bridge.cc

@@ -31,7 +31,6 @@ std::unique_ptr<EntityData> ConvertPersistedToEntityData(
     const std::string& client_tag_hash,
     sync_pb::PersistedEntityData data) {
   DCHECK(!client_tag_hash.empty());
-  DCHECK(!data.non_unique_name().empty());
   auto entity_data = std::make_unique<EntityData>();
 
   entity_data->non_unique_name = std::move(*data.mutable_non_unique_name());
@@ -47,8 +46,6 @@ std::unique_ptr<EntityData> ConvertPersistedToEntityData(
 
 sync_pb::PersistedEntityData CreatePersistedFromEntityData(
     const EntityData& entity_data) {
-  DCHECK(!entity_data.non_unique_name.empty());
-
   sync_pb::PersistedEntityData persisted;
   persisted.set_non_unique_name(entity_data.non_unique_name);
   *persisted.mutable_specifics() = entity_data.specifics;