[fixup] Add minimal webrtcdesktopcapture api for hangout services extension

Fixes "Check failed: false. Error validating response to
`webrtcDesktopCapturePrivate.chooseDesktopMedia`: Missing
required argument 'streamId'."
error after rejecting the request.

Change-Id: I3f211f7cca9a7364390f6e077bd108036bde0eef
Reviewed-on: https://codereview.qt-project.org/c/qt/qtwebengine-chromium/+/619076
Reviewed-by: Allan Sandfeld Jensen <[email protected]>
(cherry picked from commit fd5eb50)
Reviewed-on: https://codereview.qt-project.org/c/qt/qtwebengine-chromium/+/621130
Reviewed-by: Qt Cherry-pick Bot <[email protected]>

Author: mnegyokru

chromium/qtwebengine/browser/extensions/api/webrtc_desktop_capture_private/webrtc_desktop_capture_private_api.cc

@@ -140,9 +140,9 @@ void WebrtcDesktopCapturePrivateChooseDesktopMediaFunction::ProcessAccessRequest
 {
   if (stream_request_result != blink::mojom::MediaStreamRequestResult::OK) {
     // The request is canceled either by the desktopMediaRequest or the permission request.
-    // Respond with no arguments to mimic DesktopCaptureCancelChooseDesktopMediaFunctionBase::Run()
+    // Respond with no arguments to mimic DesktopCaptureChooseDesktopMediaFunctionBase::Cancel()
     // form desktop_capture_base.cc.
-    Respond(NoArguments());
+    Respond(ArgumentList(Create(std::string(), Options())));
     return;
   }