mute tab is not working

[alexwykoff]

Did you search for similar issues before submitting this one?
yes

Describe the issue you encountered:
when sound it playing in a tab, i tried to click on the speaker icon, nothing happened.

Expected behavior:
if i click on the speaker icon on the tab, it should be muted

• Platform (Win7, 8, 10? macOS? Linux distro?):
  tested on os x

• Brave Version:
  0.13.0 preview 5

• Steps to reproduce:

  1. open a tab which plays sound
  2. click on the speaker icon on the tab

• Screenshot if needed:

• Any related issues:

[bbondy]

Fixed by:
448604f

[luixxiul]

Test plan: available in the 1st post