Skip layers with protected contents from caching

DRM protected layers cause rendering issues with caching, and they can be safely excluded as caching is usually not really useful with DRM protected contents.
Bug: 190191280
Test: play a drm protected video with ExoPlayer

Change-Id: Ib3f592c4e3888e0aebdcce21d68893670d4f65d2
4 files changed