/usr/include/android/nativehelper/ is in android-libnativehelper-dev 7.0.0+r33-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/android/nativehelper/AsynchronousCloseMonitor.h
/usr/include/android/nativehelper/JNIHelp.h
/usr/include/android/nativehelper/JniConstants.h
/usr/include/android/nativehelper/JniInvocation.h
/usr/include/android/nativehelper/ScopedBytes.h
/usr/include/android/nativehelper/ScopedFd.h
/usr/include/android/nativehelper/ScopedLocalFrame.h
/usr/include/android/nativehelper/ScopedLocalRef.h
/usr/include/android/nativehelper/ScopedPrimitiveArray.h
/usr/include/android/nativehelper/ScopedStringChars.h
/usr/include/android/nativehelper/ScopedUtfChars.h
/usr/include/android/nativehelper/UniquePtr.h
/usr/include/android/nativehelper/jni.h
/usr/include/android/nativehelper/toStringArray.h