message: dcsctp: assert that CreateTimeout returns a usable pointer
  Cr-Commit-Position: refs/heads/main@{#35412}
diff: @@ -144,9 +144,11 @@ std::unique_ptr<Timer> TimerManager::CreateTimer(absl::string_view name,
  // after 800 million reconnections on a single socket. Ensure this will never
  // happen.
  RTC_CHECK_NE(*id, std::numeric_limits<uint32_t>::max());
  + std::unique_ptr<Timeout> timeout = create_timeout_();
  + RTC_CHECK(timeout != nullptr);
  auto timer = absl::WrapUnique(new Timer(
  id, name, std::move(on_expired), [this, id]() { timers_.erase(id); },
  - create_timeout_(), options));
  + std::move(timeout), options));
  timers_[id] = timer.get();
  return timer;
  }
  