Google started winning in the browser space because early chrome and it's v8 rendering engine was soooooo much faster then the competition. By 2010, web programs got much more complex and Javascript more essential, so speeding that up made everything much better. Additionally, Google's dominance in search meant that it was easy for people to find about and try it out. It got better and better, while IE was stagnant. It is likely that the EU's regulations had minimal impact on on the adoption of Chrome