Big tech companies should be all over the place. If they focus too much, they will die, because ability to change is a survival strategy in tech sector.

And this particular case seems to very strategic for Google. It's believed (inside Google too) that Facebook could be the major thread to Google, if people start searching in Facebook first and go to Google only as a second option. Thus, attacking Facebook directly is very strategic move.

And it seems to fit nicely to Android strategy too.