Potential data race prevention in AUHALStream::volume_

|volume_| can be set on the control thread and read on the rendering thread
at the same time. Declaring |volume_| as an atomic variable solves the problem.

Bug: 923844

Change-Id: I48ee9a8dfa7b7b77baa93619a08d3a0a9b989939
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1663835
Reviewed-by: Henrik Grunell <grunell@chromium.org>
Reviewed-by: Olga Sharonova <olka@chromium.org>
Commit-Queue: Olga Sharonova <olka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672195}
2 files changed