Activity log test cleanup - remove button no longer used.
The blocked api test was removed on a previous change, remove the button for
it from the options page as the button no longer does anything.

BUG=

Review URL: https://codereview.chromium.org/24502008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225593 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225593