[MemSheriff] OOM crash in LayoutTest

NOTRY=true
R=thestig@chromium.org
BUG=108832

Review URL: https://codereview.chromium.org/118443004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241684 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241684