The IHttpRequest object from the HTTP API will report HTTP download progress via a callback on a FHttpRequestProgressDelegate, which is accessible via OnRequestProgress(). The signature of the function we can attach to the OnRequestProgress() delegate is as follows:
HandleRequestProgress( FHttpRequestPtr request, int32
sentBytes, int32 receivedBytes )
The three parameters of the function you may write include the original IHttpRequest object, the bytes sent, and the bytes received so far. This function gets called back periodically until the IHttpRequest object completes, which is when the function you attach to OnProcessRequestComplete() when it gets called. You can use the values passed to your HandleRequestProgress function to find out your progress.
