Currently DevToolsNetworkTransaction is in the chrome layer so it can't be use with headless. We should perform whatever refactoring is needed to allow us to use this in headless. 

There's a discussion in the comments here about this: https://docs.google.com/document/d/1nEN0SqC1jEpHgKuQPrppwSabC8JRAuJb7MSTGCe2Pzg/edit#