GV is generally very arms length of google itself, in fact when I've pitched them they specifically say as much. They'll make investments that are supportive to the google mission generally, and sometimes that investment is a hedge I would imagine.
To add on to this, the existence of other Google investing arms makes me more believing of the claim that Google Ventures is firewalled from Google corporate; it seems Google needs Google Capital (and Google corp which also directly invests sometimes) because they can't tell Google Ventures to invest in certain companies even if they would like to for strategic reasons.
For example, Samsung is still a hardware supplier to Apple, so Apple is suing its own supplier in the Apple v. Samsung case.