[Media] Falsing protection.

Bug: 397989775
Test: manually verified with a fake falsing checkbox in the compose
gallery app. I checked that no clicks work on any button (play/pause,
prev/next, additional actions, output switcher chip), on the card
itself, or on the buttons of the guts. I also checked that swiping
between cards and scrubbing the seekbar doesn't stick.
Flag: EXEMPT code remains unused for now

Change-Id: Iba661a073bcb6cb45687ae7cd7b5277e43ed4e89