How to get all groups associated to a document library with the SharePoint 2010 Client Object Model

Using the Client Object Model, how do you get the a listing of groups that exist on a document library and remove one of them?

In the SharePoint 2013 COM, you can do this by accessing the groups collection on the on the RoleAssignments of the Document Library.  But this collection does not seem to exist in the SharePoint 2010 version of the API.

Thank you - Greg