[mrmiyagi]

the question pertains to this:
Pt(s)/H2(g)/HBr(aq)/AgBr(s)/Ag(s)

It asks why a liquid junction is not necessary. So I know AgBr is insoluble in water, and AgBr coats the silver metal. I just don't understand why it does not matter that the Br- anions from AgBr mixing with the H+ cations doesn't necessitate a liquid junction. Any help?