Robustness level capsbilities for Widevine in Chrome

Created by: danrossi

Chrome dispatches warning logs like

It is recommended that a robustness level be specified. Not specifying the robustness level could result in unexpected behavior in the future, potentially including failure to play.

Everytime it acquires keys. It seems also persistent sessions are not possible yet at least with the demos.

Shaka player has such thing exposed. The possible chrome values are these but looking at the Chrome EME sources it doesn't expose what these are for.

I am assuming HW_SECURE_ALL is hardware decryption for Android only as it failed with a key error. SW_SECURE_CRYPTO worked. So SW is software and HW is hardware.

SW_SECURE_CRYPTO, SW_SECURE_DECODE, HW_SECURE_CRYPTO, HW_SECURE_CRYPTO, HW_SECURE_DECODE, HW_SECURE_ALL

I discovered in the capabilities config it is configured as an object property but there is no external method to update this on the protection controller similar to the sessiontype.

I dug into it to expose such a thing if that is ok and tested.

About to provide a pull request.