What you are describing is not possible with, for example, Phantom. HTTP request observation is, but AFAIK the others are not. I know it's likely that Google ha

What you are describing is not possible with, for example, Phantom. HTTP request observation is, but AFAIK the others are not. I know it's likely that Google has something far more advanced / customized, but just wanted to point this out for anyone thinking about doing this themselves; it's a really hard problem to solve.