Make sure we cache the sampleTable again if using the caching datasource.

QA-impact: This fixes http streaming again which I broke about 2 days ago. The previously observed symptoms were stuttering playback of http streams (think YouTube) after a certain playback position.

Change-Id: I14050e3522ecd62c90d29310efdf508fdd2e87b5
related-to-bug: 3098873