CRAS: server_metrics - Log stream configurations

When adding new stream, metrics will log stream configurations to UMA. It
can help us do some analysis.

In this change, we record stream flag, block size, sampling rate and sample
format of one stream.

BUG=chromium:880163
TEST=Configure of stream can be recorded well on peppy.

Change-Id: I24e68d591eb9cceef304c1efbf2b99ad31c7cab9
Reviewed-on: https://chromium-review.googlesource.com/1220929
Commit-Ready: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Tested-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>
7 files changed