More TSan v2 suppressions:
 - race in media::PulseAudioOutputStream::SetVolume (issue 285242)

BUG=285242
R=tommi@chromium.org
TBR=tommi@chromium.org

Review URL: https://codereview.chromium.org/131193013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245883 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245883