This directory contains example QUIC traces. Most of those are generated from the unit tests of gQUIC's BBR implementation. You can regenerate those by building net_unittests in Chrome and setting QUIC_TEST_OUTPUT_DIR environment variable to the directory where you want those to go. The particular file shipped here, example.qtr, originally was SimpleTransferSmallBuffer.BbrSenderTest.C42.20180910211327.qtr. example.json.gz is a compressed version of JSON representation of example.qtr.