A mouse on an Android M (or later) device: (a) will no longer fire TouchEvents, and (b) will fire a consistent sequence of MouseEvents with appropriate buttons & other properties. Before this change, a low-level mouse events in Android reached blink as a touch event, hence fired a touch event then a compat mouse event if the touch event went uncanceled.
Docs: https://docs.google.com/document/d/1mpBR7J7kgTXvp0QACVjhxtwNJ7bgGoTMmxfxN2dupGg/edit?usp=sharing