1. DomName('HTMLMediaElement.webkitCancelKeyRequest')
  2. DocsEditable()
  3. SupportedBrowser(SupportedBrowser.CHROME)
  4. SupportedBrowser(SupportedBrowser.SAFARI)
  5. Experimental()
void cancelKeyRequest(String keySystem, String sessionId)

Source 

@DomName('HTMLMediaElement.webkitCancelKeyRequest')
@DocsEditable()
@SupportedBrowser(SupportedBrowser.CHROME)
@SupportedBrowser(SupportedBrowser.SAFARI)
@Experimental()
// https://dvcs.w3.org/hg/html-media/raw-file/eme-v0.1/encrypted-media/encrypted-media.html#extensions
void cancelKeyRequest(String keySystem, String sessionId) => _blink.BlinkHTMLMediaElement.instance.webkitCancelKeyRequest_Callback_2_(this, keySystem, sessionId);