Allow activity logging on DOM webkitRequestFullscreen methods

Record access to the webkitRequestFullscreen API by extensions/apps so
that it can be included in the extension activity log.

BUG=289569

Review URL: https://chromiumcodereview.appspot.com/23981009

git-svn-id: svn://svn.chromium.org/blink/trunk@157997 bbb929c8-8fbe-4397-9dbb-9b2b20218538