How Google’s long period of online dominance could end

Washington
CNN
 — 

For the better part of 15 years, Google has seemed like an unstoppable force, powered by the strength of its online search engine and digital advertising business. But both now look increasingly vulnerable.

This week, the Justice Department accused Google of running an illegal monopoly in its online advertising business and called for parts of it to be broken up. The case comes a couple of…