Modified "Empty button" > "Leave empty"

"Empty button" implies a placeholder button, which could be confusing to new users.

Change-Id: I092bdb0c8d3cfad79560526f383cdb7efb730a06
Make the default value of in-call noise suppression configurable.

Change-Id: I1dc0b6085807c49370a06243689b70ea4b91732b
Merge "Make the default value of in-call noise suppression configurable." into pac-4.4
Merge remote-tracking branch 'upstream/pac-4.4' into pac-4.4