Redwood City-based Wildfire, a developer of social media marketing software, has been acquired by Google. Financial terms of the buy were not disclosed. Wildfire--which says it now has almost 400 employees--said it will continue to help brands run and measure their social engagement and ad campaigns. The firm's software is used to monitor how social marketing efforts are performing on Facebook, Twitter, YouTube, Google+, Pinterest, LinkedIn, and other social sites. Wildfire was venture backed by Summit Partners and TransLink Capital.