On Wednesday Google said it's offering the tool, Active View, which is designed to measure whether an ad has actually been viewed.

Kevin Lee, CEO of Didit, said Google's plan is a step in the right direction. "Many would prefer that Google took its proposal a step further and allow for some form of ad engagement measure or allow for duration variables to be set longer than one second in-view," he said in an email interview

To define a "viewed impression," Google said it's using the Interactive Adverting Bureau's proposed standard: a display ad that is viewable on the screen for at least one second.