ctaRole property
primary for the one chrome action that is real click-through — opening
full screen — secondary for everything else (mute, unmute, play, pause,
collapse). Backend's PRIMARY_CLICK defaults a missing cta_role to
primary, so this must be sent explicitly on every chrome event, not left
null for the ones that should NOT count: an absent value here would make
mute/unmute/play/pause count toward CTR same as expand.
Implementation
final String ctaRole;