Analysts have been predicting that Mayer's old ties with Google might eventually lead to a closer relationship with Yahoo.
Yahoo's chief operating officer, Henrique De Castro, is also a former Google executive.
In separate online advertising development Wednesday, Google announced that users of its search-advertising system will soon have to start paying for marketing messages sent to some mobile devices, even if they only are interested in reaching people on desktop and laptop computers. For instance, there will no longer be a distinction between search-driven ads tailored for tablet computers and laptops
All the changes to Google's search advertising network won't be completed until the middle of this year.
Google says it is trying to make it easier to create digital marketing campaigns, but online ad experts say the shake-up also appears to an attempt to harvest more revenue from the rapidly growing usage of smartphones and tablets.
Google's average price for search ads has fallen from the previous year in five consecutive quarters, largely because marketing on mobile devices hasn't proven it can be as fruitful as on personal computers. The decline in Google's ad prices has been a recurring concern among investors.