Backing out the random install percentage to "20" per Chase, which will actually make 80% of users install talkback by default because of bug 300537. a=chase for checkin to a closed tree

browser/installer/windows/config.it

@@ -595,7 +595,7 @@ FileCount=$FileCount$
 ; This particular value will set the checkbox checked [number]% of the time.
 ; This logic is done only during the initialization of setup, not in any
 ; particular dialog.
-Random Install Percentage=100
+Random Install Percentage=20
 
 [Core]
 Source=[XPI PATH]\xpcom.xpi