draft proposal : active multiple devices for getUserMedia

Hi,

in these days, Constraints and Capabilities API for getUserMedia were
discussed while i found one scenario doesn't be covered:
"users may want to initiate capture from multiple devices at one time in
multiple media streams" (refer to
http://www.w3.org/TR/capture-scenarios/#multiple-active-devices).
is it possible adding the options to set the number of active devices? and
the callback function needs to change:
2.1.3 NavigatorUserMediaSuccessCallback

[Callback=FunctionOnly, NoInterfaceObject]
interface NavigatorUserMediaSuccessCallback {    void handleEvent
<http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-NavigatorUserMediaSuccessCallback-handleEvent-void-LocalMediaStream-stream>
(LocalMediaStream stream);
};
-->

[Callback=FunctionOnly, NoInterfaceObject]
interface NavigatorUserMediaSuccessCallback {    void handleEvent
<http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-NavigatorUserMediaSuccessCallback-handleEvent-void-LocalMediaStream-stream>
(LocalMediaStream[] streams);
};
br,
william