events: Fix running events-unittests under valgrind/heapcheck.

R=oshima@chromium.org
TBR=glider@chromium.org
BUG=320113

Review URL: https://codereview.chromium.org/75543003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235829 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235829