Race condition may prevent user's changes to selection of filter lists from being saved

[gorhill]

Might be related to one of the Chrome store review:

Now I know why the cpu and memory is so low. This crap doesnt even save ad filters permanently. Even the ones you subscribed to.

[gorhill]

This is caused by the fact that when a user change the selection of filter lists, the new selection is saved asynchronously, which mean the reading of the selection which occurs not too long after may cause the not-yet-saved selection to be used.