The uncertain future of Yahoo has certainly not harmed Google. The giant continues to grow, and now they have unintentionally obtained a new small chunk of customers thanks to Opera. A year ago, Yahoo was happy to announce that Opera Mobile and Opera Mini would default to using Yahoo as its search engine.
But now Opera is ditching Yahoo and opting to go with Google. While it may be a very small loss for Yahoo, it does bring some continuity to Opera products as their desktop browser already defaults to Google for search. The exact reasoning behind Opera's decision has not been announced, though the potential buyout of Yahoo could be a factor, or also the fact that Google is pushing AdSense for mobiles more heavily than its competitors.