unlockHandler = function unlockHandler ()
        {
            if (_this.context && body)
            {
                var bodyRemove = body.removeEventListener.bind(body);

                _this.context.resume().then(function ()
                {
                    bodyRemove('touchstart', unlockHandler);
                    bodyRemove('touchend', unlockHandler);
                    bodyRemove('mousedown', unlockHandler);
                    bodyRemove('mouseup', unlockHandler);
                    bodyRemove('keydown', unlockHandler);

                    _this.unlocked = true;

                }, function ()
                {
                    bodyRemove('touchstart', unlockHandler);
                    bodyRemove('touchend', unlockHandler);
                    bodyRemove('mousedown', unlockHandler);
                    bodyRemove('mouseup', unlockHandler);
                    bodyRemove('keydown', unlockHandler);
                });
            }
        }
Unlocks Web Audio API on the initial input event.

Read more about how this issue is handled here in [this article](https://medium.com/@pgoloskokovic/unlocking-web-audio-the-smarter-way-8858218c0e09).

@method Phaser.Sound.WebAudioSoundManager#unlock
@since 3.0.0