callback2.context = &callback2_invoked;
  callback2.callback = [](void* context) {
    *reinterpret_cast<bool*>(context) = true;
  };
  TFE_CancellationToken token2 = TFE_CancellationManagerGetToken(c_mgr);
  EXPECT_TRUE(TFE_CancellationManagerRegisterCallback(c_mgr, token2, &callback2,
                                                      "callback2"));

  TFE_CancellationToken token3 = TFE_CancellationManagerGetToken(c_mgr);