Straight shot always was on the GCD.
Maybe you're mixing it with Empyreal Arrow, which used to be a weaponskill oGCD you could use with Barrage before. Now it's an ability.
If it's not that, maybe what you're asking is : was straight shot always usable, then the answer is yes, cause it granted 20% crit. Now it's just a proc from Straight shot.
If it's not that, then I don't know.