id String - The identifier of a window or screen that can be used as a
chromeMediaSourceId constraint when calling
[navigator.webkitGetUserMedia]. The format of the identifier will be
window:XX or screen:XX, where XX is a random generated number.
name String - A screen source will be named either Entire Screen or
Screen <index>, while the name of a window source will match the window
title.
thumbnailNativeImage - A thumbnail image. Note:
There is no guarantee that the size of the thumbnail is the same as the
thumbnailSize specified in the options passed to
desktopCapturer.getSources. The actual size depends on the scale of the
screen or window.
display_id String - A unique identifier that will correspond to the id of
the matching Display returned by the Screen API.
On some platforms, this is equivalent to the XX portion of the id field
above and on others it will differ. It will be an empty string if not
available.
