While it's easy enough to repeat a set of actions for as many tabs as you have open in Chrome's frontmost window thanks to KM's CHROMETABCOUNT() function (which eliminates the need for a script like the one @ScottinPollock showed you):
The way I would go about this is with the For Each action, which has the advantage of letting you use its variable to select each tab automatically, freeing you from having to manually set Chrome to the leftmost tab before running the macro:
(I know it says "invalid" in that screenshot, but that's only because I'm using a local variable that hasn't been initialized yet; it works when running the macro)