This is a sample app that demonstrates how to capture screenshots based on the MediaProjection API. More on the API can be found in https://developer.android.com/reference/android/media/projection/package-summary.html Clone and import the project in Android Studio. No special dependencies and extra libraries required. Note that in order to run the code you need to create a device running Lollipop and above.
As of this writting I am getting a black screen when running the app in an emulator. Also, Android 5.1 has a bug when we check "Do not show again" box, please refer to https://code.google.com/p/android/issues/detail?id=159613.