Fix regression preventing sticky key from being enabled after moving mouse.

BUG=331399
TEST=unit test

Review URL: https://codereview.chromium.org/125533002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243262 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243262