void IVisualStudioWorkspaceHost.OnDocumentClosed(DocumentId documentId, ITextBuffer textBuffer, TextLoader loader, bool updateActiveContext)
 {
     // TODO: Move this out to DocumentProvider. As is, this depends on being able to
     // access the host document which will already be deleted in some cases, causing
     // a crash. Until this is fixed, we will leak a HierarchyEventsSink every time a
     // Mercury shared document is closed.
     // UnsubscribeFromSharedHierarchyEvents(documentId);
     _workspace.OnDocumentClosed(documentId, loader, updateActiveContext);
 }