Bug of storage.sync in firefox 52

Browser sync is a function that enable you synchronize URLRedirector options accross your devices. Before that, you need to sign in and connect with your browser account (firefox account or chrome account).

Firefox 52 support storage.sync api, but it need to be enabled manually (Firefox 53 works fine). If you want to enable browser sync in firefox 52, there are a few steps need to be done.

Steps:

1. Open a new tab, the url is "about:config"
2. Click "I accept the risk!"
3. Search "storage.sync", and double click "webextensions.storage.sync.enabled" to set it "true".

After that, URLRediretor should work find and storage options in browser's sync storage, so that you can sync the options using your browser account.