Log BIDIRECTIONL_STREAM_ALIVE before HTTP_STREAM_REQUEST

This CL logs BIDIRECTIONL_STREAM_ALIVE before we start any stream request.
This makes sure that HTTP_STREAM_REQUEST is nested inside
BIDIRECTIONL_STREAM_ALIVE begin and end events.

BUG=516342

Review-Url: https://codereview.chromium.org/2016863002
Cr-Commit-Position: refs/heads/master@{#397205}
2 files changed