Relevant Google Trends chart: https://www.google.com/trends/explore?q=google+android%2C+wi...
Blackberry's slide starts around October 2011. News search is a little more flat, but that probably reflects the fact that tech journalists like to compare the rise of one thing to the fall of another. Google search reflects what people are looking for in general, so it covers people looking up information on the phone and OS, not just news.
Oddly, Blackberry is still in the lead on image and shopping search. It was tied with iOS on youtube until recently.