The Android Neural Networks API is an Android C API designed for running computationally intensive operations for machine learning on Android Devices. NNAPI is designed to provide a base layer of functionality for higher level machine learning frameworks, such as TensorFlow Lite.
NNAPI is being ported to Chrome OS to provide a common abstraction for the implementation of on device accelerators, using Neural Networks HAL.
Vendors will provide NNHAL implementations for their hardware for acceleration on Chrome OS via ML Service.