How I figure it a bear growling at me as long as it keeps its distance is just fine, I don't know about anyone else but I feel no need to use any actions unless it comes towards me, hence why I feel you go from no force to deadly force on a animal, as its ether attacking you or it isn't.

As for getting charged for killing a bear, cougar or anything else, if its coming towards you, and you shoot it when its looking at you (ie front to back) and you report it in, I doubt anyone will be able to charge you. Just remember some places have "spoiled meat" laws, so if you shoot it and leave it in the bush you may get charged for letting it rot. Ontario for example has those rules.