In our March 2018 Delilah release we now have embedded an integrated PDF viewer.
The main reason for embedding the PDF viewer was to easily support PDF viewing from our HTML5 based version.
In the following screenshot you can get an impression of the PDF viewer:
The PDF viewer is available from the Right Click menu that is available for all result grids in Delilah.
Just a technical detail, the viewer only works when the results grid contains the r_object_id field, that field is used as a pointer to the content in Documentum.