UPDATE: OL4: https://openlayers.org/en/latest/apidoc/ol.html#.Extent
It seems that the new word for 'bounds' or 'bounding box' (BBOX) is 'extent'. See:
- http://openlayers.org/en/v3.20.1/apidoc/ol.extent.html
- http://openlayers.org/en/v3.20.1/apidoc/ol.View.html#fitExtent
- http://openlayers.org/en/v3.20.1/apidoc/ol.source.Vector.html#getExtent
One way to find out things at the moment is to run searches in the OL3 repo, for example: https://github.com/openlayers/ol3/search?p=3&q=BBOX&type=Code