CDM thunder implementation has hardcoded robustness levels

[filipe-norte-red]

Currently, CDMPrivateThunder::supportedRobustnesses() is implemented to set the supported robustness levels to "SW_SECURE_DECODE" and "SW_SECURE_CRYPTO", corresponding to Widevine security level L3 (lower). Platforms that have HW support to comply with Widevine security level L1 (higher) will not have that capability propagated to the upper levels.

Initial thought would be to extend opencdm API to return actual capabilities from the platform and set the robustness levels accordingly, but this requires some thought and review to identify the appropriate solution.

[calvaris]

From what I see here, as Filipe says, we can't do anything with the support of the the OpenCDM framework to query that information to the corresponding plugins. I guess @modeveci should pull the corresponding strings for this to happen.

[calvaris]

To act immediately while we wait for the framework support, we could either of these two things:

1. Leave it as it is
2. Remove those atoms and leave it empty as Apple does.

[modeveci]

@calvaris , I will discuss this with thunder team.