Probe both MP4 and WebM support in DrmEngine
Probe both MP4 and WebM support in DrmEngine

Issue #540

Change-Id: I908804e9334214dd4ed9d7546ce4d4d28dd69d01

TheModMaker/shaka-player,Ross-cz/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,TheModMaker/shaka-player,TobbeEdgeware/shaka-player,tvoli/shaka-player,Ross-cz/shaka-player,vimond/shaka-player,Ross-cz/shaka-player,vimond/shaka-player,russitto/shaka-player,shaka-project/shaka-player,brightcove/shaka-player,russitto/shaka-player,russitto/shaka-player,tvoli/shaka-player,TheModMaker/shaka-player,indiereign/shaka-player,TobbeEdgeware/shaka-player,brightcove/shaka-player,vimond/shaka-player,TobbeEdgeware/shaka-player,TheModMaker/shaka-player,tvoli/shaka-player,indiereign/shaka-player,tvoli/shaka-player,indiereign/shaka-player,brightcove/shaka-player