Remove unused MediaStreamAudioRenderer::GetOutputDeviceInfo

I don't recall how it was used before; but apparently it's not used any more.

Bug: 914323
Change-Id: I4c9bd365b4f2331999b973dfd09bba0dc1ced279
Reviewed-on: https://chromium-review.googlesource.com/c/1373833
Reviewed-by: Max Morin <maxmorin@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Olga Sharonova <olka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615883}
6 files changed