User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:66.0) Gecko/20100101 Firefox/66.0 Steps to reproduce: * Open Firefox in a new profile, without any policies if possible. * Open any YouTube video in a tab. * Open "Options" (about:preferences) in a separate tab, select "Privacy & Security" in the sidebar, scroll down to "Permissions". * Click the autoplay checkbox ("Block websites from automatically playing media with sound") more than one time (to ensure the change) until it is clear, then close the "Options" tab. * Refresh the YouTube tab and check the Identity and Permissions panel (test 1). * Go again to "Permissions" as above in a separate tab, click the autoplay checkbox more than one time until it is selected, then close the "Options" tab. * Refresh the YouTube tab and check the Identity and Permissions panel (test 2). Actual results: Both test 1 and test 2 show that Firefox follows the last setting, but whenever "Options" is reopened the autoplay checkbox is clear; closing the "Options" tab without touching the autoplay checkbox leaves the setting unchanged. This started happening within the 65 branch at least. Expected results: Whenever the "Permissions" section in "Options" is opened, the autoplay checkbox should reflect the last setting.

Regressed by: Bug 1512283 :alwu, Your patch seems to cause the problem. Can you please look into this?

Easy steps to reproduce: 1. Open about:preferences#privacy in Tab 1 2. Open about:preferences#privacy in another tab or window 3. Turn "Block websites from automatically playing media with sound" to on(or off) in Tab 1 4. Observe the checkbox in the other one Actual Results: The checkbox does not change dynamically. Expected Results: The checkbox on both tab should indicate same state. Before Bug 1512283, "For website that autoplay sound" selection box change dynamically. And the selection box on both tab indicates same state.

This issue will be fixed in bug1513039.