Clear ad break markers on asset unload.
Clear ad break markers on asset unload.

Change-Id: I83dd90015a591183f36ee34fe25c7591e4fadd56

tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player