cleanup: Missed review comment from crrev.com/97893002.

The TODO was relevant for the SetProperty() call, which was removed. So the TODO
should be removed too.

BUG=none
TBR=sky@chromium.org

Review URL: https://codereview.chromium.org/100333002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238211 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238211