Method AllocateBuffer

cpp/src/arrow/c/bridge_test.cc:1374–1378

      : CPUMemoryManager(device, default_memory_pool()) {}

  Result<std::unique_ptr<Buffer>> AllocateBuffer(int64_t size) override {
    uint8_t* data;
    RETURN_NOT_OK(pool_->Allocate(size, &data));
    return std::make_unique<MyBuffer>(data, size, shared_from_this());
  }

  Result<std::shared_ptr<Device::SyncEvent>> MakeDeviceSyncEvent() override {
    return std::make_shared<MyDevice::MySyncEvent>(const_cast<void*>(kMyEventPtr),