Suppress a race in IsProfilerTimingEnabled

BUG=327722
R=qsr@chromium.org
TBR=qsr@chromium.org

Review URL: https://codereview.chromium.org/102443004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240123 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240123