docs: public void trackPendingDialogCall(FacebookDialog.PendingCall pendingCall) {
          if (pendingFacebookDialogCall != null) {
              // If one is already pending, cancel it; we don't allow multiple pending calls.
              Log.i("Facebook", "Tracking new app call while one is still pending; canceling pending call.");
              cancelPendingAppCall(null);
          }
          pendingFacebookDialogCall = pendingCall;
      }