Описание тега native-activity
NativeActivity is a convenience class provided by the Android SDK that notifies native code of any activity lifecycle callbacks and makes it possible to write Android application without any Java code at all.
The Android SDK provides the NativeActivity class, which is a convenience class that notifies your native code of any activity lifecycle callbacks (onCreate(), onPause(), onResume(), etc). You can implement the callbacks in your native code to handle these events when they occur. Applications that use native activities must be run on Android 2.3 (API Level 9) or later. You cannot access features such as Services and Content Providers natively, so if you want to use them or any other framework API, you can still write JNI code to do so.
http://developer.android.com/sdk/ndk/overview.html
http://developer.android.com/reference/android/app/NativeActivity.html