Blink supports a number of nonstandard goog-prefixed constraints for getUserMedia from some time before constraints were properly standardized. Usage has gone down significantly ~0.000001% to 0.0009% (depending on the constraint) and some of them do not even have an effect due to changes in the Chromium audio-capture stack. Soon none of them will have any effect due to other upcoming changes. We do not expect any major regressions due to this change. Applications using these constraints will continue to work, but will get audio with default settings (as if no constraints were passed). They can easily migrate to standard constraints.
These goog-prefixed constraints are a relic from the pre-standard getUserMedia times and should not be used by anyone. Usage is now low enough that they can be removed without causing significant regressions.