GitLab

Also add accessor to ForwardingAudioStreamFactory.

Approximate diagram of stuff:
https://docs.google.com/drawings/d/1_ZIKj6lihGKRjq4Mflduitmkn_REqpHFeqVNelBGHHk/edit

Bug: 830493
Change-Id: I309aedf43fed5e646545eb94d00a77abc6ac66ea
Reviewed-on: https://chromium-review.googlesource.com/1039707Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Olga Sharonova <olka@chromium.org>
Commit-Queue: Max Morin <maxmorin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557111}