Build an attached LiveOverlayCompositor, or null when the
recording has no overlays to draw — in which case the caller should
capture the WebGL canvas directly and pay nothing.
Returns null rather than throwing if the mirror canvas cannot be
created: a recording without overlays beats no recording at all.
Build an attached LiveOverlayCompositor, or
nullwhen the recording has no overlays to draw — in which case the caller should capture the WebGL canvas directly and pay nothing.Returns
nullrather than throwing if the mirror canvas cannot be created: a recording without overlays beats no recording at all.