[Sync] Move ModelType and related classes to 'syncer' namespace

sync/internal_api/change_reorder_buffer.cc

Index: sync/internal_api/change_reorder_buffer.cc
diff --git a/sync/internal_api/change_reorder_buffer.cc b/sync/internal_api/change_reorder_buffer.cc
index 916ce3a07cd3aa867cd09fe4b6bf9a4b2f4a7ae7..1d7da3887d494229b7a902846789628234670d38 100644
--- a/sync/internal_api/change_reorder_buffer.cc
+++ b/sync/internal_api/change_reorder_buffer.cc
@@ -154,8 +154,7 @@ bool ChangeReorderBuffer::GetAllChangesInTreeOrder(
         CHECK_EQ(BaseNode::INIT_OK, node.InitByIdLookup(i->first));
 
         // We only care about parents of entry's with position-sensitive models.
-        if (syncable::ShouldMaintainPosition(
-                node.GetEntry()->GetModelType())) {
+        if (syncer::ShouldMaintainPosition(node.GetEntry()->GetModelType())) {
           parents_of_position_changes.insert(node.GetParentId());
         }
       }