MediaTrackConstraints: autoGainControl property
  The MediaTrackConstraints dictionary's autoGainControl property is a ConstrainBoolean describing the requested or mandatory constraints placed
  upon the value of the autoGainControl constrainable property.
  If needed, you can determine whether or not this constraint is supported by checking
  the value of MediaTrackSupportedConstraints.autoGainControl as returned
  by a call to MediaDevices.getSupportedConstraints(). However, typically
  this is unnecessary since browsers will ignore any constraints they're unfamiliar with.
Automatic gain control is typically a feature provided by microphones, although it can be provided by other input sources as well.
Value
  If this value is a simple true or false, the user agent will
  attempt to obtain media with automatic gain control enabled or disabled as specified, if
  possible, but will not fail if this can't be done. If, instead, the value is given as an
  object with an exact field, that field's Boolean value indicates a required
  setting for the automatic gain control feature; if it can't be met, then the request
  will result in an error.
Examples
See the Constraint exerciser example.
Specifications
| Specification | 
|---|
| Media Capture and Streams # dom-mediatrackconstraintset-autogaincontrol | 
Browser compatibility
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