Suppress data races between gpu::gles2::QueryManager::Query::MarkAsCompleted and gpu::gles2::QueryTracker::FreeCompletedQueries

BUG=348324
TBR=oshima@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/183763014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254381 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254381