Suppress data races in WebRtcBrowserTest.TestWebAudioMediaStream

BUG=345618
TBR=earthdok@chromium.org

Review URL: https://codereview.chromium.org/168173006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252535 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252535