Microsoft in recent years outsourced chunks of its advertising business and stuck Bing in spots that Microsoft controls or that Google couldn’t grab. Importantly, Microsoft made Bing front and center for people using search boxes on Windows computers and Office software, practically guaranteeing that a healthy share of PC owners would wittingly or unwittingly use the “decision engine.” This year it struck a deal to handle searches and ads tied to searches on Yahoo, AOL and other Verizon Communications Inc. internet properties.