Add missing data source implementation.

This is needed for clients to be able to share data with the
compositor.

Change-Id: I6b554bebe469ac2ac2c76d70cfb8ff93524826d4
Reviewed-on: https://chromium-review.googlesource.com/989492
Reviewed-by: David Reveman <reveman@chromium.org>
Tested-by: David Reveman <reveman@chromium.org>
1 file changed