Suppress a flaky test-only memory leak
BUG=298788
TBR=eugenis
NOTRY=true

Review URL: https://codereview.chromium.org/24731002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225416 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225416