I am doing a little research on the on-device Search mechanism for the Android system. I have noticed that some content, like the music I have on my device, is displayed below search results, when searching with the Google Now search mechanism. A tap on such record will open an app (in case of music it will be Google Music) with the selected content.
The question is - how is this implemented? I know about the global search mechanism (discontinued from Android 4.4) and the App Indexing API (which requires a link between my app content and website content). However, the example above is clearly local, so I do not believe it is App Indexing. And if not that, then what?
I have found this form from Google, which seems to correspond to my problem, but maybe there is another approach I know not of?