Will extensions be able to ask for the permission at install and then be able to use it in the background without having to explicitly ask each time? I ask bec

Will extensions be able to ask for the permission at install and then be able to use it in the background without having to explicitly ask each time? I ask because it's useful to be able to draw an image to canvas to then extract image data without having to parse the file format in javascript. Having to pop up a permission dialog each time would simply annoy the user.