Helper which manages provides computed request sizes as well as transparent decompression.
Note that request compression is not officially part of the HTTP standard however it is
commonly in use and can be conveniently supported here.
To use, invoke
createBodySink(java.lang.String) to prepare an output stream where the raw body can be
written. Then invoke
getDisplayBody() to retrieve the possibly decoded body.
Finally,
reportDataSent() can be called to report to Stetho the raw and decompressed
payload sizes.