Remove friend declaration for nonexistent class UserGestureIndicatorDisabler.
Remove friend declaration for nonexistent class UserGestureIndicatorDisabler.

This class was removed a few months ago:
  https://codereview.chromium.org/1006313002/

Review URL: https://codereview.chromium.org/1237463002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@198794 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk