Disable autoclick delay dropdown in settings page when autoclick not enabled.

BUG=325112
TEST=manual

Review URL: https://codereview.chromium.org/103263002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238777 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238777