HAR export support

There exists a very handy tool for performance analysis called BrowserMob Proxy. It allows you to capture HAR files for any browser by acting as a simple MITM proxy. It does not support SPDY, HTTP 2, or TLS, though. Proxygen could be an ideal replacement, if it had the ability of recording requests and outputting them as HAR. I see that there already exists code for reading / replaying HAR files in the test suite code, so I'm wondering if recording HAR files is on the horizon.