This bug covers necessary platform work for fixing DevTools bug 1617852

Summary

It looks like the transferred (response body) size for the final channel is used for all preceding channels in the chain.

This is probably related to the fact that DevTools don't have API to track response bodies for redirections and thus using the final response's size only.

More details

• DevTools is calculating the transferred as well as real size of responses here:
  https://searchfox.org/mozilla-central/rev/070a000dd49aac4a26147e137efcd91a728d13b8/devtools/server/actors/network-monitor/network-response-listener.js#477-479

• It's part of nsIStreamListener we register for response bodies
  https://searchfox.org/mozilla-central/rev/070a000dd49aac4a26147e137efcd91a728d13b8/devtools/server/actors/network-monitor/network-response-listener.js#191

• And also part of nsProgressEventSink callbacks
  https://searchfox.org/mozilla-central/rev/070a000dd49aac4a26147e137efcd91a728d13b8/devtools/server/actors/network-monitor/network-response-listener.js#382

See the original report bug 1617852 for more details and a test case

Honza

Nhi, this needs prioritization, thanks!

Honza