Reland "Bind StreamFactory in audio service."

This is a reland of 21f2ef4cb6ad89be9ca765afe7a3f1d077d726f2

Per offline discussion, this code is fine.

Original change's description:
> Bind StreamFactory in audio service.
>
> Bug: 803102
> Change-Id: I4d8cb112445095045c492488f7c3b8d9853b6c23
> Reviewed-on: https://chromium-review.googlesource.com/1004634
> Commit-Queue: Max Morin <maxmorin@chromium.org>
> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
> Reviewed-by: Olga Sharonova <olka@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#549481}

Tbr: 
Bug: 803102
Change-Id: I3b14b633dd1419eae570d2b9ab411fc8732fad4c
Reviewed-on: https://chromium-review.googlesource.com/1005080
Reviewed-by: Max Morin <maxmorin@chromium.org>
Commit-Queue: Max Morin <maxmorin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549504}
8 files changed