It looks like there is a regression in SU2017 where SketchUpViewerAPI.dll is missing from the SketchUp installation directory.
As a work-around users can copy the file from C:\Program Files\SketchUp\SketchUp 2017\LayOut to C:\Program Files\SketchUp\SketchUp 2017 and the sample should work again.
Can you see if the example works for you by copying over the DLL?
This issue has been filed internally and we’ll get it updated in next release.